It is objectively pointless to make such an argument. He was very aggressive, but who is to say he was wrong? His adrenaline was no doubt flowing, he had no idea if the second guy was going to come at him with a gun, he had no idea if this guy would find some sort of super human strength to come back at him --- it's impossible for anybody to dictate what a person should and should not do under those circumstances. Walk a mile ... but one thing he did, he stopped when the guy said, please stop. That shows some compassion / humanity.

Personally, I believe part of this type of anger and aggressiveness at fighting back is due to the fact that so many people have felt helpless when year after year the so called 'authorities' do nothing and let criminals get away with their crimes. Also, he probably doesn't deal with this on a regular basis. So when he had his chance, he went for it -- all out.