We know that. This is old news. As Chris Hitchens correctly points out, had President Bush up and run from the room instantly, then THAT would be what they would point to as proof he "knew" it "was on". Or they'd simply say he scared the kids and rattled easily and he did not demonstrate cool and calm under stress (which he did).
Please read my link and excerpts at post 70 for the thoughts of someone in the room at the time.
Much appreciated!