Your conclusion doesn't follow from your premise -- you're using flawed logic. What would you think of an oncologist whose patients never contract serious, life-threatening cancer? Is he ordering unnecessary tests and procedures on people who aren't really sick, or is he catching all the cancers so early that they're never life-threatening?
See the point? I'm certainly not arguing one way or another about the TSA, just that your argument contains a very serious logical flaw. Maybe terrorists, knowing about the TSA, won't take the risk of going near an airport.
> ... so there's no reason to believe it would have handled this incident.
Flawed argument, flawed conclusion.