I have had dealings with people who told me the CIA was following them...both were Schizophrenic. ..not excusing him...just saying the TSA should have seen problems...he should have been no where near a gun!
The FBI took his gun from him.
After questioning him, they gave it back to him.
If they are that inept, they need fired, at least. Anything other than total incompetence on someones part shows willful negligence.