This is exactly why MGM and maybe the concert promoter will be sued in perpetuity over this event and why there may never be another concert in view of a high rise hotel. Heck, they may start x-raying luggage when you check into hotels with high pedestrian foot traffic within shooting distance, which is almost any hotel along the Strip.
Hotel and parking lot cameras will reveal how he brought the in....they’ll be able to follow all his steps....