It's up to the pilots union now. What the union is asking for is that any pilot that wants to carry can do so if they pass the fed agent shooting course. I read a news clip that the FAA has:
1. never approved any training course, and
2. just changed the regulations so as to NOT permit airlines personnel to be armed.
It's up to the pilots union to insist, and Congress to change the law. Congress trumps the bozos at the FAA.