It is the job of anyone handling a firearm to handle it in a safe and responsible manner.
You don’t get to pull “not my job” when you were holding the firearm that killed someone.
Especially since the normal on set was so far below the industry standard - a fact I would expect somebody with is broad and extensive experience to know as a qualified actor.
He had a duty of care to check the weapon and to handle it safely and he didn’t.
He had a duty of care to not point a fucking lethal weapon at people, and he did.
(This is in addition to potential liability as a producer and a duty of care to ensure workplace safety.)