Ever looked at the hallways at Mandalay Bay? Didn’t think so. As the maintenance worker pointed out, there are deep recesses at the room doorways, lots of potential hiding places, contrary to your theory. They can be seen in this video by some idiot:
https://www.youtube.com/watch?v=R_BUbhm7Bj0
Ever consider how fast rounds would be coming at him? Didn’t think so. No chance he would have been able to run to a doorway. Unless he really is Jesus.
Drywall isn’t much of a barrier