What ifs can be equally as disasterous? Interesting conjecture. Particularly since no one has "tested the theory". They just assume, as you did, that "it would be bad". Very scientific conclusion. (That's satirical!) Inadmissable.
I contend that if there were armed persons in schools, it IS possible that, at the very least, SOME damage control might be managed. You wrote that off, too. (Apparently I'm not the only citizen that feels it might do some good, there is widespread support for concealed carry in colleges... particularly after the VT incident a couple of years ago.)
Your "answer" to the problem, then, is the status quo, rather than trying something that might have some promise at helping resolve the damage. (For NOTHING is ever going to completely stop the occasional nutjob from trying to take out his frustrations on the nearest "soft target". INCLUDING Gun free zones!) It's just one of those little facts of life that continuously makes a lie of some people's version of a completely safe and sound life here in the US.
I beg your pardon, no one ever promised ANY of us a rose garden!
Incidently, the past experience on "gun free zones" is that it does nothing to prevent a nutjob or a bad guy from going armed in them. It only (really) affects decent law abiding citizens and the potential opportunity to defend themselves. Even at that there are no guarantees.... but a small chance of success is better than no chance at all, IMHO, of course.
In fact, the "past experiences" that DO exist tend to demonstrate that there is no one present in gun free zones to immediately take action to prevent a high body count. That much is obvious. The alternative? Do away with the gun free zones. At least have the guts to experiment with the idea.
Every time a topic that loosens gun control comes up, the immediate, knee jerk reaction is for the anti-gunners to proclaim "That would be BAD!" Generally without a lick of evidence to be able to show that a valid "excuse".
Just like the "Castle Doctrine" adoption in the various States. Every State it is introduced in legislature, the immediate hue and cry is that "the streets will run red with blood" makes the headlines. EVERY TIME! (I guess it's because the gunaphobics can't think of anything original to claim.) Then the legislation passes.... and GUESS WHAT? The streets DON'T run red with blood. EVERY TIME! (You would think that at least one of the gunaphobes might take notice of that little "coincidence". But, no! It's same-o same-o and utterly, utterly predictable, their "fear factor" claims.)
Thus, for your plea to "sway public opinion", I don't believe that is a very logical approach. Mainly because the gunaphobics are NOT logical, nor can they be "swayed" by simple rhetoric. About the best we can do with them is keep a close watch on them and keep them on a short leash. (Don't want them spreading their crap too far afield.)
Fanatics: Cannot change their minds. Will not change the subject.