I find it strange that we keep beefing up physical airport security when things like this happen. We have so much front-of-house security (and little security for employees, oddly), but we can’t get the intellence part down? The most important part of air security is failing. Various organizations track and watch various individuals, but don’t communicate, and they end up on a plane with a bomb, the very place that the intelligence organizations were banning them from being.
Case-in-point, stop slowing down and hassling travellers with body scans and banning books (yes, books) as carry-on items and focus where it matters: intel and inter-organization communication. If he’s watched for being a threat, then check him out before you let him on a plane. You don’t need to check everybody’s inner organs to figure that out.