I have trouble seeing how someone can believe both A and B at the same time:

A) "The moment someone tries to take your gun, you should assume they're trying to kill you, and from that moment on you have the right to preemptively use deadly force."

B) "If a random man approaches you gun-in-hand and shows no badge, you should NOT assume he's trying to kill you, and you don't have the right to use ANY force in response."

In self-defense, there's a general principle that you don't have to wait for someone to *actually* try to kill you before using force.

If you extend that principle to the men who killed Arbery, then you should also extend it to Arbery's attempt to grab the gun.

Also, it's irrelevant whether the man pointed the gun at him or simply carried the gun while issuing a demand.

If I demand that you do something, and lift up my shirt to reveal a gun in my waistband, that's an implicit threat to use deadly force if you don't comply...(cont'd)

...At that moment, you have the right to use preemptive force in self-defense, including trying to disarm me. Crucially, you do not have to wait and see if I make good on my implicit threat to try and disarm me...(cont'd)

If you are thinking "he wouldn't have gotten shot if he hadn't lunged for the gun," you're totally right and totally missing the point by starting the story in the middle: i.e., he also wouldn't have gotten shot if they didn't pull up on him with guns to begin with.

FWIW, I agree that left-wing media sources tend to push the racism angle regardless of the facts, and is only interested in covering white-on-black crimes (never the reverse). Still, neither of those observations should color your interpretation of this particular case.