This policy by itself: perhaps not. He did skip a room cleaning one day before the shooting, but he quite probably could have worked around one if he knew it was coming as a matter of policy. It is, however, just one of many changes made, all of which in concert (no pun intended) would make something like that at least significantly harder to do.
For instance, he had bell desk bring 22 large suitcases to his room over a few days. That's a huge red flag that would not go unnoticed now (and there's likely some procedure about logging/reporting since then). Prior to that event, nobody logged or even paid attention to such things. When you work with whales in Vegas, you just get used to eccentric rich people being eccentric rich people. Now you're at least aware of threats from people posing as them.
For instance, he had bell desk bring 22 large suitcases to his room over a few days. That's a huge red flag that would not go unnoticed now (and there's likely some procedure about logging/reporting since then). Prior to that event, nobody logged or even paid attention to such things. When you work with whales in Vegas, you just get used to eccentric rich people being eccentric rich people. Now you're at least aware of threats from people posing as them.