Noam Chomsky is an exceptional and brave truth-teller. In an interview with David Barsamian in November 2001 he said: "We should not forget that the U.S. itself is a leading terrorist state." But his views on 9/11 are indefensible.
In an April 2009 interview on the "Little Atoms" podcast, Chomsky said, "My suspicion is that the Bush administration was very pleased with the rise of the 9/11 movement, because, whatever one thinks about it, I don't think much, but whatever one thinks about it, if you believe in it, its effect was very clear; it diverted people away from activism on serious issues. So, if you're spending your life trying to figure out whether there was thermite in building 7, and so on, you're not protesting the crimes of the administration," (0:41 to 1:18) in the video below.
Chomsky's point of view can be summarized in one word: wrong. There is no other way to put it. Smart men are not always right. Chomsky is a genius, but even he is plain wrong about the role of the U.S. government in the 9/11 terrorist attacks.