You're assuming that the power-grab of government is all-encompassing, and that all parties collude equally. I doubt this is true.

Even congressmen are human, and at least some were caught up in the emotion.

Cynically (and I expect downvotes) I even imagine Bush caught up emotionally, as old-school Cold War vets Cheney and Rumsfeld finally saw a chance to pounce on popular fervor to increase executive power. Perhaps I'm wrong, but history seems on my side.