Jumping off your post.
IMO, if Police Chief's short, yet to the point statement is true--MB assaulted OW, a struggle for the gun ensued, and a shot was fired--then OW had no choice but to stop the the threat MB posed.
Those are the actions of an extremely dangerous, and violent person. That is a protocol that is most likely never, ever, never going to change. An officer in this situation has a duty to protect himself, and the community at large. assaulting an officer, and attempting to take his gun is never going to be an action that police are taught to tolerate, or that it's a situation which can be negotiated.
Of course this argument only holds if what the Police Chief said actually happened. And IMO, the fact that Parks has been forced to admit there was a "serious altercation, his gun coming out, and a shot fired" tells me that's exactly what happened.
JMO