The thing is… there really wasn’t (and likely won’t be, at least in our lifetimes) an alternative.
I’m not any sort of 2A die-hard either; I’d much prefer that we live in a society without guns everywhere, as in the civilized rest of the world.
However, we don’t. This is America. Giamanco wasn’t faced with a “trolley problem” in some abstract ethical debate. He had a few seconds to decide “Oh shit. This guy is about to shoot up the school, and my kids are in it. What do I do?!”
He would have no way to know whether law enforcement could arrive in time, and whether they would be able find and neutralize the mass shooter before they were killed.
He chose the only course of action left to him: intervene or watch more kids, possibly his own, die from inaction.
Lucky for his kids and the other survivors, he had the mental fortitude, equipment, and (presumably) training to successfully intervene without collateral damage.
I don’t see how that could make him anything other than a hero.
If he had chosen to do nothing at all, he wouldn’t exactly be a coward… running away from such a situation would be the natural thing to do for just about anyone. But it would probably have made him a bad parent if something had happened to his kids, and I bet he would never have been able to live with himself after that…
I’d argue he had both the ethical right, and the parental obligation, to do exactly as he did. That he did so, successfully, without causing any other injuries (as far as we know) should be celebrated — just as it should be if an undercover police officer, or a proper uniformed response force, did the same.
It is sad that we live in a society where this is the only realistic avenue left to parents in his situation, but so long as it remains such a society (i.e., where 2A trumps schoolkids’ lives)… he did the only thing he could, and did it well.