Well...
If the guy on his back, on the ground getting pummeled did it, it would be sort of understandable, to get the other guy OFF of him and stop the punishment.
In that situation, whatever you do to avoid being killed, goes.
But it appears as it if it was the attacker that did it.
Just psychotic...
Anything can happen when you get in a fight. I once prosecuted a case where a guy with one arm got in a fight with a guy with one leg. Yes, address of the incident had the word “lot” in it.
That was Tyson's victim's comment. That in the street it's one thing, but in the ring there are rules to follow.