Clinton would never have seen that acting decisively, taking political risks in defense of the nation, as potentially generating support for himself. The first bombing of the towers, the attacks on Americans abroad -- after none of these attacks did he act in any meaningful way. Remember that at each election he got less than a majority of votes. To take the nation to war, acknowledging an act of war against us, would have turned his base against him, and he'd never have had the vision to consider that the rest of the nation would support him.
Taking the 'tin-foil-hat' shot is cheap and easy and meaningless.