Its certainly not a deterrent as currently applied. It would only be a REAL deterrent if EVERY pilot was an FFDO. The "cop" straw man is just that.

A real terrorist will just roll the dice considering the number of FFDOs to the general pilot group.

But that's always Barney's excuse. If the Captain had been an FFDO on the German Wings Airbus would the outcome have been any different?

Virtually ALL terrorist threats have originated on International flights. The whole FFDO programs is a knee jerk reaction to 9/11 capitalized on by a bunch of gun nuts who thought they were going to get unlimited concealed carry authorization just because they were airline pilots.