Oh, please. Let's all pretend like nothing like that could happen.
Why does race even come into it? The man had a GUN. That's G-U-N. (BTW, that's not directed at you, Howlin, just at the race-baiter argument). To me, that's reason enough to check him out, no matter what his race is. What I can't figure out is why AA didn't call the USSS to check the guy out. The number's in the phone book, for Pete's sake, usually with the emergency numbers.
And where was the agent stopped: the ticket counter, the metal detector, or the gate? And if it was the latter, how'd he get by the first two? And what time did the agent arrive at the airport, because he should have arrived early enough to allow for thorough screening.