Tennessee

Mistake #1: He brought a weapon to school, and was obviously seen brandishing it.

Mistake #2: He fired shots at the SRO.

Mistake #3: Were they supposed to wait and see what he did next?

What would the outcry be if they had tried to negotiate and talk him down, and then he shot and killed one of the responding officers or the SRO?

I would have some sympathy for his parents. UNLESS, it was they who gave him the gun or allowed easy access to firearms within their home. Then they have to suffer the consequences for their actions. But at least they might get their gun back, so there's that.