I assume that is a joke, or am I reading this correctly. You want someone who isn't a pilot to come and sit with you with a gun everytime someone goes out to the toilet. Why are you on this forum?
Do you have another efficient solution ? Not "someone with a gun", as you write improperly : a
police officer or an agent from an enforcement agency with a gun.
I don't see why this couldn't be debated here.
As a passenger, and as a long-haul pilot's and former army fighter pilot's son myself, I would certainly be reassured by such a disposition.
No psychiatric test whatsoever will permit to detect if, when and how a psychopath will act. My wife is a therapist herself and she knows she will not meet some patients
alone in her office — borderline is borderline.
And please, aggressiveness is of no use here, a bit of decency won't do no harm. I took precautions in what I wrote, with some caveat.