The security guard now has armed security guards. I guess his employer is a paying to keep him under wraps.
That could be for a host of reasons:
1:To keep him safe from the media's 24/7 paparazzi pestering.
2: In the event others are involved, to keep him safe from any reprisal/threat (assuming unknown conspirators working with the gunman exist) or in case of that possibility.
3: To keep the reporters away so he doesn't say something that can be twisted around and made into something it is not.
4: To keep ambulance chasers and personal injury lawyers away from him so they aren't badgering him into making statements which might reflect badly on the hotel.