The gun was prop. A defective prop. No different than a stage light falling on someone because it wasn't properly secured.
Even a person trained in handling guns, would have probably done the same because the expectations were that it was nonfunctional prop. Of course, someone who has handled firearms before would have questioned the gun and inspected it for themselves.
“Agreed. And I don’t blame him unless it can be proven that it was intentional.”
You forgot the /s
“The gun was prop. A defective prop.”
Apparently it was not defective!
“Even a person trained in handling guns, would have probably done the same because the expectations were that it was nonfunctional prop.”
Source for “nonfunctional prop”, please.