Completely stupid idea, coming from a hyper paranoid society hell bent on destroying everything they don't know anything about. If in doubt, shoot it.
Having spent the past two weeks on domestic US carriers and travelling through 15 of so US airports, the lack of obvious security was frightening so it's now not surprising aircrews are taking the law into their own hands, because that is what it is. A discharged weapon, a shot passenger, an injured crew member leaves debate open for a certain few valid arguements.
No thanks to flying in the USA again or on a US carrier