They do know that he did not check in at the Chicago hotel overlooking Lollapalooza. He did check at the hotel in Vegas during the “Life is Beatiful” festival, which was held at the same venue that he fired on. They must have some internet traffic on him, as it’s come out that he searched for hotels near Fenway Park. Who knows what that means..
He was a millionaire, retired and apparently stayed in hotels quite often, and traveled a fair amount (ex., 20 cruises).
The fact that he booked a hotel that overlooked another concert at that location isn't really saying much if he routinely booked hotels in vegas (concerts everywhere, often) or elsewhere.
Now, if there is no record of him staying in a hotel in vegas prior to the "Life is Beatiful" event...then I'd say there's something there!