I find that leg wound interesting. Was he shot from the front or back? Why was he shot below the belt and not above? I think the shooter knew this guard well, guard could have been a messenger. Tells shooter the plan is not going well because someone backed out. Shooter shoots "guard" in anger and then himself because he knows the game is up, he's on his own.
I think the guard should be investigated also.
I don’t think the security guard was Paddock’s focus or concern. He shot at him enough to get him to retreat and that’s that. Paddock’s focus was the concert crowd and apparently the fuel tanks located past the concert field.
In the manic zone of running to windows shooting, killing the security guard probably was not a priority.