Chad Nishimura is no where to be found at this time.
Here is a copy of that story
http://yournewswire.com/mandalay-bay-valet-missing/
If you feel like going a little deeper down the rabbit hole, there's this.
It just so happens that some dude with a bunch of similar weapons with bump stocks and 900 rounds of ammo was arrested in Tennessee the day after Mandalay according to local news there. They did a search on his residence and found a bunch more stuff and evacuated 8 surrounding houses while doing so. Apparently explosives.
Funny it didn't make national news. Some sources say this guy was in Vegas on Sept. 26 or 27th, and had met with Paddock. And of course, the weapons weren't registered and nor did they have any serial numbers. Just your typical hunting enthusiast.
The video linked below also contains information about the FBI holding someone(maybe Chad?) 47TH Floor OF MGM VDARA Resort as well as the Tennessee arrest.