I don't think you're wrong.
I have to agree with that as well. From the layperson's perspective, I don't understand why the dead guy's past wouldn't be brought up, since he initiated the physical stuff, but I don't see how the shooter's past would not be brought up as well, because it's just too related to his behavior before the physical part of the incident started.
That doesn't mean I think the shooter should be prosecuted. There is still the law and reasonable doubt, and the initiation of physical contact by the other party. It's just the more I read about the shooter, this is kind of going to be like a first amendment case, where someone says something stupid and disgusting, but their rights have to be protected just like anyone else's.
As I said earlier in the thread, if the shooter had been circling my vehicle, I'd be prepared to go to condition orange. If he pulled his gun to wave it around to show me he was a tough guy, I'd likely consider it a threat to my life and shoot. Again, the dead guy wasn't the one in the car, and all I said about him earlier in the thread still holds, which is why I (barely) give the shooter the benefit of the doubt.
As was pointed out elsewhere here by zxcvbob, this is really a case of "When aholes collide".