I mostly agree with you that self-defense (or not) arguments tend to be in the moment, although motivation seems to be a factor in the arguments, whether it should or not.
I think the Atlanta bunch honestly believed he was a prowler.
I think at some point after being chased by the pickup trucks, Arbery believed his life was in danger. Maybe that’s why he (allegedly) grabbed for the shotgun.
In the struggle, it went off.
Its hard to believe this won’t wind up as aggravated manslaughter. But both sides have a story to tell, and if there’s any background info, I’d be curious to hear it, especially as I’m not on the jury.
Aubrey case is knotty. Pretty clear Aubrey was casing the construction site to rob it, if not actually robbing it. Reasonable for neighbors to chase down a suspect. However, armed apprehension of an unarmed suspect by common citizens is something YOU DO NOT SCREW UP because if you do, you’re screwed. They did, they’re screwed. Whatever crime he was up to, and whatever right they had to confront him while armed, he felt threatened and grabbed the wrong end of a gun. They’ll be hard-pressed to demonstrate they were properly performing a citizen’s arrest where the suspect felt in fear for his life and attempted, poorly, to mitigate what he thought a threat.
Sometimes both sides are wrong, and things end badly.