If I were the armed/soft clothes police detective, I would calmly & politely remind the restaurant employee about the small town police dept officers who were shot in a diner in WA state a few years ago. A deranged gunman walked in & shot the uniformed cops as they ate.
There was a 24hr Whataburger place where I live that offered discounts to sworn LE & armed, uniformed security officers. The young kid on the night shift once told me; "if you have a badge & a gun, you get the discount.".
This Denny's sounds like an isolated incident. I wouldn't go there.
ps: The Whataburger restaurant is closed now.