Even Disney tries to keep "incidents" from getting out, so other guests don't panic. I really think that's what happened here with the hotel, and police were not engaged until well after the initial incident.
After all, if he was confronted by hotel security before the windows were broken, and other people shot, then the hotel probably just thought it was a nut job that would threaten people inside the hotel.
This is kinda like a "9/11 type wakeup" on the fact that a shooter on the new strip has unprecedented access to all sorts of nearby areas ... from the airport to public areas. I mean, there's a reason why the "old strip" started well north of the airport.
This was just naivity, ignorance and ... very likely ... not taking cues from similar, European resorts. We Americans will have to learn. Unfortunately, those resorts are really, really close to the airport.