Regardless of motivation, this is probably too little, too late. Mainly because the notion that "[s]uch accusations, unless successfully rebutted by the administration, could be politically troublesome" doesn't really fly with me. They're rebutting just like they usually do: "Nope, we're good. You media people really shouldn't be questioning us on this." And that usually seems to be end of story. Obviously, I'm exaggerating, but it never seems to take much for them to convince people that issues are non-issues. Maybe some day something will stick, but I'm not counting on it.

Also, and again, the Bush administration certainly didn't take the al Qaeda threat seriously. Maybe Clinton's administration at least considered them a threat, but they clearly didn't do much, either. There is, of course, the Iraq issue, and I think there's a case there. While previous administrations weren't doing shit about terrorism, at least they weren't doing extra useless and potentially dangerous shit like planning a war for revenge/oil/empire/whatever. Sure, we've gotten involved in military action and other shenanigans, but nothing quite like the load of total horseshit that is the Iraq war.

"His critics have said it is disingenuous and cynical to make that association."

Yeah, no fucking shit it's disingenuous and cynical, and this is coming from the king of both. If I've said it once, I've said it a million times: Iraq had nothing to do with 9/11. The Iraqi invasion was decided on a long time ago by people like PNAC, and all they needed was some excuse - any excuse that the stupid American public would buy - to follow through with it.