Let's step through the confluence of events.
First, the Detroit bomber's dad contacted our government and said that his kid had radicalized and that Pops was worried about what Junior might do. Then young Umar Farouk Abdulmutallab pays cash for a plane ticket to America. For good measure, he takes no luggage on this international flight.
Were I king, I'd have diverted his flight straight to Guantanamo at this point. Save a few steps.
But let's review what we actually did. Was he stopped? No. Was his explosive-laden self searched? No. Did we so much as put him on the No Fly list? Uh-uh. Did we revoke his Visa? That would be rude. No, the sum of our government's response was to put a note in his file that maybe we shouldn't renew his Visa when it expires in June.
Fantastic.
What does a whackjob gotta do? Carry a bowling-ball candle under his arm as he boards?