FBI doesn't always share that kind of information until they've finished their investigation or unless they need help from the public. They're in charge of this part of the investigation per last PC.
Two more things:
1. JC said when he called security the second time to tell them there was gunfire on the floor, he didn't tell them he was wounded as he wanted to get off the radio quickly so others could use the frequency. I wonder if the people at security didn't take him seriously about gunfire and delayed calling 911.
2. If JC said he heard the drilling noise while in the area next to the fire door, MGM may try to pin him with liability by saying he should have recognized it was gunfire. JMO, that would be wrong, but not surprising for a big corporation trying to save $$. That's why JC's union needs to have his back (and they do) to prevent the employer from throwing him under the bus. JC needs legal representation and I hope he's getting it from the union.
Easy to see the initial confusion over the timeline due to the noises that sounded like drilling, etc. The part left out of this interview is the communications after JC reported shooting on the floor. Clark Co sheriff said JC called security on the radio and on his cell phone. JMO, JC called them a second time on his cell to see why they hadn't called 911 or to clarify that he'd been shot. He didn't want to use up the radio frequency so others could communicate.
There's probably a dispute between JC, LE and MGM over this part and is why we haven't heard a 911 call yet. It probably went out later than it should have. Hotel security probably didn't believe JC when he reported gunfire or didn't think it was serious enough to call LE (crazy, but possible). MGM is pressuring LE and JC to support whatever scenario they're trying to come up with to explain the delay. The CT about multiple shooters, etc. also helps MGM because it serves to confuse the public and muddy the waters when they get to court for the civil lawsuits.
ETA: All JMO