Let me preamble this by saying I know I am full of crap. But I think the 9/11 commission and all it’s attendant grandstanding is *really* about iraq and the current state of the country. It’s not that he won’t apologize for brushing off the warning signs (all of us did), but because he won’t apologize for *anything*.
You said it yourself–he won’t take responsibility for anything. If he apologized for something–it doesn’t have to be about 9/11, maybe he could apologize for treating our allies and the UN so poorly during the leadup to the Iraq war, for example–it might actually strengthen his image. Now he has turned into an all-or-nothing tug of war. It can’t be won.