Basically, with the information I have and what I can infer, I don't think 100% of the blame is on the teacher. I think a theoretically well-intentioned system of trying to honor everyone finally backfired. Badly.

The old rule of thumb was that if you couldn't say something nice, say nothing at all. So what do you do when saying nothing isn't an option?

And now that I've thought about this more for a few minutes, I think I'm going to ramble and rant a bit....

I think the "everyone gets a trophy" theory is a well-intentioned but horribly executed idea. What I think we really meant is that everyone needs to feel loved, to feel valued, and to feel like part of a community. But instead we are recognizing people for being outstanding at something when they really aren't. You can be loved, valued, and part of a community without being outstanding at anything, and vice-versa. Like many things, we've substituted the difficult thing (showing people they are loved, valued, and part of the community) with the easy thing (giving them a trophy) and pretended they are the same.

Maybe this teacher is "just" an idiot. Maybe they were willing to suffer the blowback (either being disciplined or fired) to make a point. At least when they reached the point where they snapped from the lunacy of the world around them, they did so with a tasteless joke instead of with a weapon or explosive device.