EDIT: Just noticed the pics you posted. I'm going to say that holster doesn't count as OC, in contraction to everything I posted. To me, that holster is the equivilant of carrying my revolver in a belted camera bag.
To my knowledge, NV law does not address this issue. The only thing I can relate to your situation is that the definition of a Concealed Firearm is one that is carried in a manner not discernable by normal observation. In English, that means if I can look at you and easily notice that you're carrying a pistol, you're not concealing.
If you put that holster on your belt, and it looks like a holster with a gun in it, I'd make the arguement that its OC. Sort of like the older US Military holsters:
NRS 202.3653 Definitions
1. “Concealed firearm” means a loaded or unloaded pistol, revolver or other firearm which is carried upon a person in such a manner as not to be discernible by ordinary observation.