I normally avoid the word 'gatekeeper'. It's used by conspiracy theorists to dismiss those who disagree with them. But there is one exception. Noam Chomsky's grasp of logic is unrivalled. He figured out that language is innate, not by empirical evidence (that came later), but from first principles. His one-sided, moralistic clichés about U.S. imperialism are boring but mostly harmless. More insidious are his views on Palestine, which can fairly be described as 'gatekeeping' - he is deliberately shielding Israel by pretending that supporting it is in the interests of US imperialism:

'It is understandable that Palestinian rights should be marginalized in US policy and discourse. Palestinians have no wealth or power. They offer virtually nothing to US policy concerns; in fact, they have negative value, as a nuisance that stirs up "the Arab street". Israel, in contrast, is a valuable ally. It is a rich society with a sophisticated, largely militarized, high-tech industry. For decades, it has been a highly valued military and strategic ally, particularly since 1967, when it performed a great service to the US and its Saudi ally by destroying the Nasserite "virus", establishing the "special relationship" with Washington in the form that has persisted since'.

http://www.guardian.co.uk/commentisfree/cifamerica/2012/feb/15/imperial-way-american-decline-noam-chomsky

Nothing could be further from the truth. Standing on the shoulders of Michael Neumann and Jeff Blankfort, I demolished all of these excuses in 'Faithful Circle - A Response to Noam Chomsky's Book "Fateful Triangle"'. President Eisenhower supported Nasser. The reasons the Palestinians have the negative value of stirring up the Arab street is because of Israel. The USA doesn't support Israel because it is wealthy; it is wealthy because the USA supports it. Etc. etc. etc..