Don't care for the penultimate graf, but rep and respect for owning up for your earlier remarks.
Maybe, as you contend, Arbery would be alive if he had dropped to the ground and begged for his life, but the situation is so completely surreal that it's unfair to judge. Imagine if you're out for a Sunday jog and suddenly around a curve there's a truck with three dudes armed with shotguns who are yelling at you to halt. Three cops drawing down on you in that situation would be bewildering enough, but three rednecks?
What if Arbery had turned and run the other way? Preponderance of evidence suggests this "posse" likely would've shot him in the back. There's also no telling what the folks in the trailing vehicle would've done.
Instead, he tried to run around the truck, but then got shot at (hard to tell conclusively from the video, but this seems the most likely scenario). In that situation, charging the shooter seems reasonable because your back is going to make a much easier target for him and his buddies.
Worse, even if he had wrestled the shotgun away from Redneck No.1, there's no doubt Nos.2 and 3 would've gunned him down the moment there was any separation.
So, yeah, maybe he should've fallen prone and yelled, "Massuh, massuh, doan hurt meh, pleez!" the moment he saw the roadblock, but why should someone minding his own business have to publicly debase himself to a trio of strangers simply for taking a Sunday jog?
Even then, it seems quite likely that these trigger-happy idiots would've found some justification for shooting him, which means this Arbery guy was fucked no matter what he did.