Define - Plausible Deniability
I'm no one of authority, but I believe GWB was duped into being president (he never wanted to be president, he wanted to be baseball commissioner.) and was kept in the dark on the plans for 9/11.
I think he knew of the Abel Danger war games that were going on and was completely shocked when he was told what happened sitting in that chair reading to those kids.
He was kept in the dark for a while for plausible deniability and was threatened to keep his mouth shut.
I also believe he flipped, think biggest.