The trial is over, it was self defense therefore TM was the attacker.
GZ was carrying a gun. The greater burden was on him to do anything he could to prevent the situation or, if unavoudavle, to prevent escalation from occuring. He did absolutely EVERTHING wrong. Does that make him a murderer? I dunno. Does it make him responsible for the situation existing in the first place? F*ck yes. Without that gun, he would NEVER have been there confronting TM and never would have been creating the situation.
He should NEVER have put himself in that situation. That's the the key. As a person carrying a gun (but not a LEO), he willingly created a situation where someone died.
To be perfectly honest, as much as I love shooting (at the range) and hunting, that is one of the reasons I rarely carry a weapon.