Probably because this did not have to end up in a shooting.
Open carry, and pulling the gun very early affected the outcome. The same thing can happen to a police officer. A furtive move from a odd behaving individual can lead you to draw your weapon. If that same bizarre behavior continues, your options for self defense are limited by having the gun out. Drawing a gun and getting a non-compliant response (”go ahead and shoot me!”) definitely makes things a lot more dangerous.
The attacker was going for the citizen’s gun. The citizen had little choice having backed away into the store to avoid this confrontation, where he was attacked repeatedly and continuously. Unfortunately he had few other options besides being disarmed.
What am I missing here?