Everybody is saying "why couldnt they just make a call and verify the guy's identity?" as if that's a trivial matter. Do you understand that size of the organizations you are talking about? I doubt that it can be done in an hour, given the level of security held by secret service agents working in the president's detail.
Frankly, I agree with what was said: this was a case of airport security more-or-less doing their job... he fit the profile, he was armed, his reason for flying was suspect. An ID card was not a good enough reason to let him on the plane.
Keep in mind that the guy with the shoebomb was also detained by security and actually allowed to fly the next day. This is not an exact science and never will be. There will be plenty of errors made on both sides of the right/wrong line.
Ron