Off-duty LEO -from another jurisdiction-. Just another legally armed civilian at the mall at that point.  Note the opposition from the anti-gun rights fanatics to the Fed law allowing out-of-jurisdictional carry by LEOs.

And nice "fear-mongering" with the anti-gun rights new bugaboo "open-carry." Was the off-duty cop open carrying? Did the poster you replied to mention it? Then why did you bring it up? Read, think and speak with precision if you want to be taken seriously.