Interesting theory, but that requires one of two things:
Waiting until the weapon is actually pointed at you before taking action, or shooting an individual who stops taking aggressive action once they see that you are capable of meeting force with force.
In the above situation, that would have required me to either wait in my home, knowing that the shooters would return. This would have given a distinct advantage to the aggressors, and allowed them to attack at their own leisure, perhaps even after I was asleep..
Instead, I choose to meet them away from my home, in a situation where I chose, and allowed me to keep them away from my wife and kids. It also allowed me to retain a tactical advantage, which I needed all I could get. The police were (judging by their previous response times) 10 minutes away. If I had allowed 6-8 attackers to get out of their cars, what would my tactical situation be in taking on 6-8 attackers, as opposed to taking on two car loads before they could exit their vehicles, and separate?
Since I made that choice, the only option left to me was to shoot a person who ceased his attack as soon as I pointed a weapon at him. Would you suggest that I shoot a person who drops his weapon as soon as I point my gun at him?
Difficult tactical AND legal situation. I maintain that if I had shot the bat-boy, the situation would have been over at that point.