So, are you saying you should not pull if some attacks you with just fists? Why not just a knife? Using my gun is a "disproportionate use of force" to a knife.
I think the point is that "Derkotch was the aggressor". He may have just asked why he son was not getting to play more and the coach was an a-hole and started screaming. Derkotch then stood his ground because you are not expecting a coach to start hitting you, but that is what the coach did.
If someone starts beating on me, I will pull my gun to stop it. Period.
Also, the media can is know for leaving out details that would make it look like the gun owner did what was needed.