You seem to be conflating what is and what isn't self defense, actively chasing someone and threatening their life isn't a case of self defense which is what all 3 individuals did.
I'm not conflating anything.
Have you all forgotten that he was holding an AR-15 style rifle??
If someone walks away from you a bit with a rifle, would you just automatically assume you are safe?
Someone walking away from you with a rifle is meaningless. What if he was just getting some range between himself and the people pursuing so he can get a better shot without getting apprehended himself ? I'm not saying this was Kyle's intention, but this is my argument about perception. How did the people in the vicinity know what he was thinking?
Pursuing him was still a self defense option. In fact I would say in the heat of the moment, actively pursuing and trying to disarm the rifle carrier could be perceived as the safest option. This wasn't a knife or a baseball bat. It was a rifle.