I don't see it that way
You're making a movie and they hand you a loaded gun?
It's a movie set
Real bullets should have never been in a gun given to the main actor or anyone ...
But that's what they did.
There's someone in jail for that negligence.
I gave an example if the director had you drive a car with no brakes
Would that be the actors fault too?
On top of this the movie is a western with gun violence?
And the hand you a loaded gun???