This is likely the case.
However.
Let the victims see every detail on the perpetrator's last days. Why hide?
Let the victims see every detail on the Mandalay Bay's operation. Why hide?
Let the victims understand the measures that will be taken by the hotel and security in the future to prevent similar massacres.
Every outdoor gathering is a potential killing field.
We need to understand that this event is being used to the benefit of future events. Much like lighted exit signs became part of building codes around the country.
Alas, publicizing that which need not be publicized rarely ends well. Innocents involved will be harassed. Businesses will be sued, if only for doing normal business.
The only group here that need be scrutinized is the police: the long response time means every responsible agent should be fired for incompetence, setting an example for the next group to deal with scenarios decisively, removing every barrier thereto.
“Measures taken by hotel & security”, beyond actually putting video cameras in every hallway, will do little short of extreme intrusion. I’m not going to a hotel if I have to go thru metal detectors to enter. For similar reasons I rarely fly, preferring to drive 1500 miles than submit to 4th-Amendment-violating “security theater”.
Yes, every outdoor gathering is a potential killing field. That’s exceedingly rare.
Yes, sometimes the dragon wins - that’s no reason to hide in caves and disarm the knights.