Let's face it, if the 9/11 attacks were "legitimate", they would have been accompanied by "legitimate" statements and claims of responsibility.
You don't pull off the most spectacular "terrorist" attack in history, especially against largely symbolic targets, and then hide.
You don't put yourself through the expense, trouble, risk, etc., of carrying out the most daring "terrorist" attack in world history, only to let a panel of fatuous government apologists tell the world what your ostensible motive was; e.g., "they hate us because of our 'freedom'", or some such puerile nonsense.
Moreover, someone totally committed to the idea of stopping U.S. imperialism/aggression against his people, country, etc., and willing to die to do it, obviously wouldn't have to be tortured into admitting it. I mean, contrary to what the U.S. government would apparently have us believe, an ideologue doing a 9/11 would be different than, say, a greedy person doing in his rich uncle to collect the inheritance money.
Lastly, any group sophisticated and resourceful enough to have pulled off the 9/11 attack, would be sophisticated enough to get their message across, exactly as they wanted it to come across. Perhaps by sending (a few days in advance), an encrypted message, "open on 9/11", to a few dozen newspapers and government agencies in several countries, the UN, the Red Cross, the Vatican, various internet sites, etc., and then, immediately after the attack, have an associate release the encryption key.
Let's face it, the whole point of "terrorism" is to make a point. What good is "terrorism" to the "terrorists" if the "terrorists" don't get to make their point? That would be like robbing a bank, and then giving the money back.
Thus, like many other aspects of the official government conspiracy theory of 9/11, it simply doesn't make sense.