There’s a background check involved in getting the badge.
Well, sure - it's an employment check the airlines do, even for the flight attendants, but certainly for pilots, and even more so if they're in the program that allows them to carry concealed on board.
Funny, though, how the baggage handlers have virtually the same access, but very little employment screening.
I'm personally amazed the muzzies haven't either themselves or using a compromised baggage handler, introduced a suitcase bomb into a jet somewhere... or maybe they already have (those "missing" airliners).