I guess we know that if terrorists had tried to fly an airplane into a building in DC again, they'd have been able to do it. If a slow plane like a Cessna 150 can get close enough to cause evacuations, just think how close a fast plane could have gotten.
When I was a student pilot on solo cross country flights I always knew where I was and I always made sure I knew where not to fly. It shouldn't happen, but I can see how someone may stray off course now and then and drift into the edge of a towered airport's space. But freakin' Washington DC after 9/11? There's no excuse for that, and what's worse is this student had an instructor with him. The student should have known better, but the instructor should have really really really known better. I think they're damn lucky they weren't shot down.