I know the guy who's behind the crimeseen security system. Trust me when I say the restaurant owner probably didn't want the sign, but it was the guy who owns crimeseen that pushes the policy of a pro concealed firearm sign as part of the overall security package. He's a former regular here at the OKC Coworking Collaborative and he came down to SXSW in Austin a few months ago to talk about his product at our OPEN BETA event.
His security system is pretty good and part of the deal is not just the implementation of a security system, but also in education and how to deal with potential security situations if you're home alone, ect.
Most places balk at the idea of welcoming legally owned firearms, but he makes it a point to add those signs as a part of the overall security package and educates why having pro firearms signs is essential to security of a location. I highly recommend anyone interested in a security system to check him out at crimeseen.com or PM me if you want me to directly connect you to him.
If you do talk to him, tell him that Tommy from the OKC CoCo sent you.