Whether he was wrong or right, he was stupid. I was taught in my CCW class never to use your weapon unless you are prepared to spend the next 10 years in prison to prevent what you are trying to prevent. In other words, if someone is about to seriously hurt or kill your child, I'd be willing to spend 10 years in prison to save their life. I would not be willing to spend 10 years in prison to "detain" this guy the cops could have found anyway. Also, this guy pulled the first gun. Whose to say the dead guy wasn't defending himself. In this state, they would prosecute.
Only because he was more practiced. The reason the CCW holder drew was because he thought the other guy was "fumbling" for a weapon, which, as it turned out, he was. Prior to that time he had only asked the guy to remain until the police came.