Movies are make believe. The director yelled “cold gun”, and Baldwin the actor was entitled to believe him.
The one role he had that may expose him to criminal guilt is as producer. He apparently hired an an incompetent and inexperienced armorer to save money, and as a result it is reasonable for him to share in her obvious guilt.
I agree (when I accuse Baldwin, it's "Baldwin as Producer"), and apparently The Law agrees, as well.