That's the crux of it. To me, it's a binary condition--you're either in grave danger and need to use lethal force, or the danger isn't really that imminent so you (illegally, unjustifiably, unsafely) fire warning shots.

The big thing is, he says he was just trying to scare the dogs off, but he still managed to hit one of them. Good shootin', Tex.

I can see their line of thinking, though: that he was in a situation where lethal force was justified, and they simply didn't use his own testimony against him. Which, ultimately, is laudable. I would rather have the courts act on that principle than try to prosecute unnecessarily.

All the other points are irrelevant. He was dumb to have his dog off-leash to start, but that doesn't invalidate his right to self-defense.