Yep, Kids and guns should NOT be mixed !!
What if it was loaded and some kid picked it up intending to take it to the office, he drops it, it goes off, and kills kids ??
In addition, IF some kid HAD picked it up loaded or not- he/she is taking a big risk.. they could be expelled carrying a fire arm... no matter what their "honorable" intentions. Some unscrupulous guard (fearing losing their job) could claim the kid picked it up (instead of being guilty of leaving it unattended).
Point is, as you imply... it opens a big whoopazz can of worms !!
MY biggest complaint is I don't want kids growing up fearful that if they're not under the protection of armed guards, they can't feel safe !! That's NOT the America I grew up in but that's what we're becoming !! A F-ing Police State !!