I haven't been following the Arbery case, but I can't even imagine what the defense would be. I imagine the defendant can argue in the moment Arbery grabbed his gun, he felt his life was in danger and it was defense. And I imagine that is actually true.

But this occurred while he was in the midst of committing a violent felony, driving down the guy armed vigilante style, so he would be guilty because of that. Sort of like when a drunk driver causes another motorist to hit and kill someone, they are guilty of the murder, because their felonious act caused the murder.