IMHO the best way to cancel flights with out anyone knowing, would be to have all the airlines quietly send all their money back with no reason.This way no one would be the wiser, and nobody would say anything. They would just not show up at the airport.
So why the heck they didn't let everyone board, take off then laand at some local military airport ...?
If the pilot is the bad guy, that's not likely to happen. There's a good chance that by making this cancellation loudly public so quickly, other known AQ at different locations were spooked and disappeared into the woodwork to jihad another day.
Or maybe not. The press is as much a tool as it is a problem. They can easily be played if necessary.