If nothing else, it would be nearly impossible to observe Rule #1 properly in such a situation. Muzzle control is still important, even when the weapon is holstered and the trigger well-protected.
The same could be said with horizontal shoulder holsters... it's always pointing at the person behind you...
I'm of the firm belief that there is no such thing as an "AD". In order for the gun to go off, the trigger needs to get pulled -- whether a person thought
the weapon was unloaded when they were hammering down, or a the person was holstering the weapon and something was obstructing and got caught in the trigger... it involves negligence
on the part of the person.
If a weapon is secure in a holster with the trigger covered, there is no way it's going to discharge unless someone pulls the trigger. The fact that they're around other people, young or not, is not a factor and is a common reason used by anti's as to why people should not be allowed to carry in malls, grocery stores and on campus.
For me, the concern would be more focused around having proper retention in place to prevent the gun from being unholstered and the belief that a gun can 'just go off' really needs to be quashed.