This is particularly true if Paddock really was a lone wolf.
Since he is dead, there will be no trial.
The only reason to keep known information away from the public would be if there were other parties involved. Those other parties include members of federal agencies.
I think this is the most likely scenario. It explains both the secrecy, the coverup, and the Sheriff's stress.
The real questions are if this was essentially a just as planned
operation, or an operation that went sideways
. The latter is bad enough, and would tarnish a government agency that likely cannot afford to take the PR-hit, but the former is more interesting
in that it shows the government willing to either cause or allow Citizens to die.
Also, if the latter be true, the question becomes Why?
— and it could have a multitude of possible causes. First, the speed that the gun-control push (and legislation) came out of the woodwork is astounding and indicates that, if nothing else, they had it waiting in the wings
. Second, it could have been to prop up the war fever
for the War on Terror. Third, it could have been to introduce new security technologies and expand agencies like the TSA. Fourth, it could even have been something as stupid/petty as pushing the whole NFL/kneeling thing out of the news because it was hurting them/investors/donors financially. Fifth, it could have been to muddy the waters
and create diversion politically; remember that there's a lot of interesting possibilities in the works (like Anwan brothers).