If the police have no legal obligation to ensure your safety, why should a private security-guard?
It’s not an issue of legal authority at its core.
It’s a moral issue of protecting a girl being stomped in the head, which is a murderous assault.
Any male human who would move OUT OF THE WAY of thugs stomping a girl on the head, is not a MAN.
ANd I don’t give a damn what his security guard contract says. IT’s far beyond that.