Sure they would have. More likely, the guy wouldn't have even tried it in the first place.
If this was a presidential visit, every hotel room with a sightline to the event would have been vacated and locked down. The security measures that are going to be expected for large events like this are going to be approaching that standard ... which is why I suggested these events are slowly going to disappear.
What security? He was a hotel guest, if you think Vegas hotel security will start searching ever hotel guests bag you don’t know much about Vegas. Big events like this are normal here, they aren’t going to “lock down” the hotel everytime.
Also, police found multiple weapons which explains the different sounds. AR or AK is not hard to make full auto or just use a bump fire stock.