Not really, that’s just one (extreme) proposal. I understand the self-gratifying impulse to write something like that though: it absolves the responsibility and work of addressing the problem, and frustrates the conversation away from finding solutions toward justifying the need to find a solution at all. It even makes you feel clever for a half-second.
This is a principles based analysis. Pretty common in public policy.
Principle 1: Children should not be victims of arbitrary violence
Principle 2: Children should be educated
These are compatible principles. Your proposal (one of many potential proposals) is to undermine principle two rather than addressing the source of the issue which is violent third parties.
And to forestall any further swiss-cheese a priori logic: this is not something fantastical. There are other societies with have honored both principles one and two, and have experienced zero, as in ABSOLUTELY zero acts of mass violence in educational settings.
This is the only moral choice when dealing with absolutes.