“But I very much doubt that was the case.”
AB is an Ahole.
Screwing around is nearly his whole portfolio.
Though the 4 rules of gun control may not be The Law, they are a Very Good Idea and likely should be.
AB is 100% responsible.
Others may have liability in addition to that of “The Talent”.
AB may very be an a-hole, but whether or not he is responsible for this in the manner you suggest is an open question. He may very well have civil liability as a producer for not having hired competent staff and for allowing production to continue even after earlier gun safety incidents.