I think you are giving the feds credit for a lot more proficiency than they have displayed at anything else in recent decades.
Everyone is looking for one answer, one guy or one group, to blame for this tragedy.
It is like an onion. Peel off one layer, there is another. Peel that, another one. The whole time you are peeling, the smell gets worse.
There were multiple ‘events’ going on that night.
President Trump was there. The Saudi Prince was there. The DHS was there. The FBI was there. They were conducting a terrorism exercise. There was an anarchist group of members from various ‘anti-white’ groups who wanted to use the cover from all the confusion generated by the aforementioned sentences to carry out the (in the words of the mystery woman who told the crowd before the shooting) “you’re all gonna die”. The alleged shooter owed the casino a ton of money. The alleged shooter had worked for CIA/FBI/LOCKHEED and the IRS. There were shootings at other casinos. There were two unidentified helos. And on, and on.
Anyway, it was something that the CIA/DHS/FBI lost control of, but not all of it was due to their lack of proficiency.
The cover up is mainly because the CIA/DHS/FBI don’t want the public to know that they got snookered, while they were trying to snooker us.