If this latest victim were more aware of what was going on around him and had a concealed sidearm, it would have been a much different outcome. Simply keeping eye contact with the attacker probably would have been sufficient to keep him at bay and moving on to find a more desirable target. Putting a hand on his pistol and letting the perp see it would have had the little bastard running. There's a third scenario but no sense in using deadly force unless you have to.
In between is the scenario most likely in this case: with that much “in my space” time, the punk probably would have had the opportunity to tell me how clean the bore of my carry piece was — with my finger still safely off the trigger...