I may sound flippant at times, about firearms, but in reality I am not. Turning and shooting someone intentionally (and unintentionally) is a real hazard. It has happened many times. The Chris Kyle (American Sniper) and Chad Littlefield shooting in 2013 is a perfect example.
It's no different in rock climbing of course, as you say. Someone gets belaying or a knot wrong, or some other such thing, and it's often a long way down.
I'm not very liberal with trust, I'll be honest; It takes effort to gain it, and to retain it. A simple, seemingly harmless comment or act, can see it evaporate in a moment.
!ENGAGE 20