“What was Mandalay Bay’s security doing during all this?” - -
I suspect there’s not a whole lot hotel dicks can do in a situation like this, other than to see to the safety of guests and pray the SWAT team gets there fast.
I suspect that Mandalay would have a more sophisticated set up than a couple of hotel dicks. I was thinking less about stopping the perp than collecting and disseminating info to LE, protecting guests, assisting evac. And I suppose it was too much to hope that a proactive security team catch the perp before he could do anything. Ex: a guest who refuses maid service for days should at least rate a visit from security, a knock on the door inquiring if everything was ok.