Because every rational person knows it's very likely that someone is going to run at a man holding a shotgun and punch him in the mouth while attempting to wrest the gun from him.
Why that's predictable as the sunrise. Every man holding a shotgun gets immediately attacked by some unarmed man attempting to take the weapon away from him.
The moral here is "don't ever hold a shotgun." Someone will run up and hit you in the mouth and attempt to take it away from you.
Only stupid people think someone with a shotgun will not be attacked. You have to be a real moron to believe that a shotgun will stop an attacker from hitting you.
Yes, very stupid of them to not realize they were just asking for a physical attack by holding that shotgun.
Almost as stupid as starting the story in the middle.
There was a whole lot that led up to Arbery being in close proximity to someone pointing a shotgun at him. The jury in the criminal trial was privy to, and took into consideration the parts that you conveniently omit.