Putting my tinfoil hat on for a moment...

I wonder if there was a threat against the airline? Perhaps something enough to be credible but not so specific as to be pinpointable, and rather than cause widespread panic by saying "ground every AA flight until we sort it out" (which would freak people out beyond belief), someone figured out that pulling the plug on their mainframe for a few hours would have the same result without the panic. Just some pissed off passengers.

Or maybe I've just been watching too much Homeland. Sigh.