When a respected dissident, someone who is extremely critical towards the government and usual not shy to blame it for rather sever acts, essentially states "this time it's not the government - relax people it's not always a conspiracy" - he acts as a very effective "gatekeeper".
This one person has the power to hold back a lot of people who are on the verge of outrage about government foul play. This one person's opinion could either open or close the floodgates for people demonstrating, rioting and asking big inconvenient questions that can not be ignored - if there are enough people.
There are various reasons to suspect Noam Chomsky could have limits for how far he can go in criticizing the US government. Here are some reasons that hint towards an agreed limit or self censorship from Chomsky's side, making him a possible "gatekeeper":
- Apparently the government provides him with (undercover) bodyguards when he is on the MIT campus .
- He has not lost his job like other dissidents do - instead he has one of the best jobs and environments to keep his criticizing going.
- There are no obvious attempts from the governments to silence him in the past decades other than the usual underreporting in the news and possibly supporting the bad branding of the term "gatekeeper".
- He sides with the government's position in highly suspicious areas like 9/11 and the JFK assassination. Many of his "followers" expected to be at least doubtful.
Noam Chomsky does, however, point out at various occasions that he is disappointed that some see him as the leader of a movement. For example here is his response to the showing of the multiple award winning documentary "Manufacturing Consent: Noam Chomsky and the Media":
And if the impression is given that there's some leader or spokesman or something like that organizing, galvanizing things, that's absolutely the wrong lesson. The lesson there is follow your leader. The lesson ought to be: take your life into your own hands.
I think Chomsky's contributions over the past decades were enormous. He has publicly criticized the US and the corporate media more than anyone I know or have heard of. However, would it be surprising that even he has limits. Why shouldn't he? Why should he be the only one who can step outside the system and speak publicly and openly against media and self-censorship without impacting his work's reputation and safety?
I do not expect any of my teachers, parents or other idols to lead me all the way to my goals. I do, however, expect them to help me develop my abilities in their areas of expertise. Most importantly, eventually I expect to wean myself off their guidance and become independent.
Our parents have their limits, our teachers have their limits, Noam Chomsky has his limits. Even Jesus (if you believe), according to the bible had his limits. Chomsky has criticized the US in over 50 excellent referenced books and tirelessly spread his message of being critical. For many years he has been the most cited scholar on this planet. He has done an amazing job raising awareness of US politics and media manipulation.
Bruce Lee, the legendary martial arts artist, teacher and actor once said something very profound:
You must protect your students from your own influences.
I think Noam Chomsky is doing his best to do just that e.g. by pointing out he is not a leader. However, many of his "listeners & readers" have inadvertently become "followers" and regard him as a leader nevertheless. A leader has - per definition - great influence.
The world-class Finnish education system, today, is based on the assumption that a good teacher provides, among other things, information, sources and a learning friendly environment but limits his own influence. Finnish teachers are told not to lecture or coerce their opinions or even knowledge. The liberty and with it the responsibility of the student is valued highly.
Examples of system critics who may have lost some authority because they crossed the "big issue line" are David Icke and Alex Jones. Stepping across the government tolerated boundary is risky also as it means you could be wrong in a very big issue which would severely harms your credibility. Both Icke and Jones are - in many ways - a different "variety" of critics when compared to Chomsky. One difference is that, after stepping across the (big issue) line, thanks to the governments defense propaganda, both of them and their work were automatically branded "conspiracy nuts" - no matter if they are right or wrong.
For both this means facing more credibility problems because they have the corporate/government controlled media against them. This is the price they paid for not being "gatekeepers". Chomsky is only battling underreporting while those two battle underreporting and aggressive media hostility aiming to ridicule them.
I would say for the mainstream media there are essentially two kinds of dangerous system critics: "gatekeepers" and what has been branded as "conspiracy nuts". Gatekeepers, system critics who stay away from certain (too) big issues in favor of staying in the game, are respectfully under-reported while risk taking "conspiracy nuts" are either ridiculed or ignored. This ensures that everyone including the government & corporate media are relatively safe and changes cannot occur too fast.
I believe both types of system critics are important assets in the fight against propaganda and power abuse. Both attack their common enemy from different angles and often with different weapons. Most importantly, they appeal to different groups of people although there can be some overlap.
Eventually we humans may realize that it would make a lot of sense to set aside the relatively small differences and join forces instead. We have created an enemy that is likely too big for any single group of dissidents. In fact, a successful fight against corporatism would need the combined power of many groups: left and right, "conspiracy nuts" and "gatekeepers", black and white. The power system's build-in divide and conquer/weaken strategy has branded these (now) common terms and generated very effective distractive polarization among the population.
It is not much different if you think of a father - son relationship: one generation creates the groundwork for the next. The father may well be hoping that his children will one day become independent from him and be able to go where he did not choose to go.
Think of a father who chose to speak up against a military dictatorship which got him killed before he could educate and raise his children. This father may have been right but probably not wise or effective. He could have waited until he raised many rebels or even devoted his life to training even more rebels while dodging the dictator's radar and staying alive.
Obviously, the people who represented the US government (and most others) did benefit tremendously in terms of monetary gain and power from the 9/11 attacks. As a convenient side effect, their biggest credible critics may lose some influence as they have only two inconvenient choices: Step over the big issue line and ridicule yourself or stay quiet and be branded a gatekeeper. The term "gatekeeper" itself - in this context - is already successfully negatively branded through its association with being a "government/new world order shill" or "master propagandist".
Until recently, presidential candidate Ron Paul had a similar problem with the 9/11 truth movement - often called the "truthers". He would be the obvious political choice of that movement. as he clearly represents true change and integrity. The truthers themselves, however, stepped over the big issue line long ago and were branded conspiracy nuts. To many truthers' surprise and anger, Ron Paul realized the branding problem very soon and learned to stay away from them - even if he totally agreed with them.
The open support of a relatively small group that has already been (in my opinion: often falsely) ridiculed for years by mainstream media propaganda would likely kill his chances. It took a while but eventually, it seems, the truthers realized this dilemma too and stayed mostly quiet. Hopefully they still vote for him as he would be the only candidate who would likely act in their interest, once he got elected and does not rely on mainstream media so much.
Along similar lines, if Chomsky openly supported the 9/11 truth movement, he too would become at least partly branded as conspiracy nut and lose much of his credibility. For those of us recognizing these dilemmas - I believe - the right thing to do would be to support them, consider their limits and start thinking for ourselves.
Who are we anyway to blame them? What did we do? How many people have done what some of us expect Chomsky to do (open the gate, stay credible, survive and pave the path to the gate for others)?
I would not be surprised if Chomsky was secretly quite happy to see that many people discover his "role" of a "gatekeeper" - which he obviously couldn't talk about without losing credibility on both sides of "the gate". However, it cannot be totally excluded that he really believes that e.g. the chances the truthers are right are small.
Alleged "gatekeepers" like Noam Chomksy have done a lot of the dirty, dangerous and difficult work for us - we can't expect them to do everything and risk their lives too often. I think we should eventually grow up and think independently - which is what system critics advocate all along. If there were 100s of gatekeepers like Noam Chomsky, millions of outraged people would see and be able to walk up to these 100s of gates easily and safely. We would surely be closer to discovering who is behind the gates - much closer than without their help.
[update August 2012:] Here is another angle on the issue: Chomsky clearly and repeatedly stated that (not only) the US government benefited from 9/11. In other words..
if the US government benefits from such terrorist attacks, is it reasonable to trust the government to do its best to protect the country from future terrorist attacks?
Why would such a government had tried hard to prevent 9/11 ?
The same could be said about the benefits and motivation of the mainstream/corporate media.
Maybe Noam Chomsky is not a real gatekeeper at all..
 Noam Chomsky's info page in the jewish virtual library
 Chomsky explained why he has not seen the film Manufacturing Consent: Noam Chomsky and the Media, in an interview with Movie Guide (p. 11 of the companion book to the documentary by Mark Achbar, 1994) - read part of it in footnote 1 here