I was slightly torn on this one from a technicality standpoint, but not about the simple logic of it all. Disclaimer: It’s been a while since I read all the details on this case.
For some reason, the armorer somehow allowed live cartridges on set and that is super bad. However, anyone that holds any kind of weapon should treat it like a weapon, especially if it is not marked as a prop or isn’t visibly disabled.
It was a failure of the top two gun safety rules: Always treat a gun as if it is loaded, and, never point a weapon at anything you do not intend to kill.
The death of Brandon Lee years ago should have underscored how even prop guns can kill.
Edit: Are there points that are incorrect here? Weapon safety is super important…