I feel badly for this vet, but restaurants offering such promotions should require some evidence of service. A DD-214, VA card, Legion or other veteran's organization card, etc.. I went to one such promotion, and they checked nothing. And while I'm sure most of the people there really were vets, it would have been easy for a faker to get a free meal.
I go because I like meeting some of the other vets. Went to a Golden Corral -- crowded as all hell, probably 2/3 black, mostly older. My stepson and I sat across from a woman and her child, started talking, etc.. She'd been in the Navy (definitely legit) for 6 years in IT -- actually worked with White House communications at some point in the Pentagon.. Shook hands/fist bumped some older Marines there as well.
One thing I really like about it is that as soon as you walk through that door, race doesn't matter. We're all (or mostly all) vets, and everyone is friendly to each other. Then you walk outside, and it's a different world again.