Perhaps he was given a mission to test security, and report back to someone. Perhaps he wasn't given any more information about a potential plan, so he couldn't rat out anyone.
Very odd, in any case. Don't these people know how much more difficult it will be to hijack a plane now? Unless their plan is to just kill people on airplanes, which will be pretty hard, as well.
good point about testing security...time for the INS to release a report of all those whose visas have expired...time for winter cleaning so we won't have so much to clean in the spring. Semper Fi, Mike