Well, just to follow through on this thread ...
the question I would have is ...
exactly how straightforward and easy is it to remove one of these windows and then replace it?
I've seen shattered office building windows replaced, and it certainly was NOT a quick and easy job.
I would think that ... if there were shooters on another floor ... and their plan was to temporarily remove a window and then put it back to make it look like they were never there ... they would have to be able to do this ... and clean up all their brass and haul all of their equipment away ... very quickly ... in order to get away and make it look like they were never there. With the hundreds of cops around and in that hotel, that does not seem very plausible.
I think the cops would be able to tell pretty easily if another room was used for shooting thousands of rounds onto the ground below.