Bret I have to disagree on this point, to deliberately allow someone to commit an unsafe act, when I can stop it makes no sense.
I have stopped more than one from an AD at ULSC because I saw the round in the chamber. Have I been able to stop everyone, no I haven't. Many of those were due to "speed unloading" which prevented me from seeing the chamber.
This is different from telling a shooter they forgot to insert a magazine. The failure to insert a magazine is not an unsafe act, unintentionally lighting one off at ULSC is. The RO is charged with "monitors safe competitor action" (7.1.1). I don't read monitors as acting as a potted plant, but to take proactive actions if possible. To not stop a competitor from committing an unsafe act, if possible, would make me remiss in my duty as a Range Officer.