Hypothetically, if this was a conspiracy, then Bush's involvement would have been at the very most listening to options and then selecting one. For the same reason I can, in the same sentence, say that America invaded Iraq and that Bush isn't a trained soldier.
(For the record I don't believe 9/11 was a conspiracy.)
Quote from 911sharethetruth.com:
"""Initially, most of us fell for their version of the events. But then came the slip-ups. The leaseholder of the World Trade Center admitted on PBS in 'Rebuilding America' that WTC-7 was 'pulled' on 9/11 (See video here in Windows Media Format - http://www.911sharethetruth.com/extras/SilversteinBdg7.wmv), which is the standard slang for controlled demolition.
Look at the tapes from that day when TV anchors, Aaron Brown and Dan Rather first said the very same words about the collapses. Firefighters and rescue workers talked about explosives and bombs going off, all over in the buildings. Recall the horrific images of the over 100-story towers coming down at free-fall speed, defying the laws of physics. Recall the engineers who first stated that the planes and fires alone could not have caused the deadly collapse. Now the evidence is gone, witnesses silenced, and an independent, real investigation never happened. Sure, it is hard to accept that we have all been fooled so long, but only discovering and facing the truth will set the U.S. free.""" - 9-11 Truth Activist of Northern California
As for the politics, whatever. Bush/Cheney allowed 9/11 to happen. And then they capitalized on the aftermath. So what? There's no evidence that is actionable. You're outraged? Big deal. While you're refighting past battles, the bad guys are gleefully stealing your future.
Having said that, the 9/11 Truther groups are basically cults. No different than the La Rouchians, Scientologists, climate change deniers, Clinton Killed Vince Foster, etc. People addicted to anger busy disempowering themselves.
Behind every fad or movement, there's someone making a back.
Just think, wouldn't those who run the world spend just several hundred lives and two buildings to gain a so profitable war on terror, the Patriot Act, and a new permanent enemy (the terrorists!) to keep the people in terror and pull more and more of their rights to "protect them".