Terrorists are, generally, useless.

[weemadando]

But that's the whole point - average joe will get annoyed that his post keeps getting delayed because the post office is shut down every second day, or his flights keep getting delayed because of the continual delays that stack up at airports.

Of course everyone in a "security" role will be on edge, but the fact is that these incidents just have to be designed to be as innocuous as possible in most scenarios (so the guy who misses a flight catches the one he rebooks onto without any issues etc). The whole point is to make people fed up with the security precautions further hampering their activities while running the emergency services ragged. That's the theory behind this kind of scenario.