My guess is you are mandated by law to post a no guns sign if that is your general policy. But like I said, this appears to have been special circumstances prompted by a particular customer’s irrationality. It might have been better to explain to the malcontent that they were cops. Anyway, businesses usually reserve the right to refuse service for a panopoly of reasons. For instance, just be ause they post “no shoes, no shirts, no service” does not mean you can wear shoes and a shirt with no pants. I don’t see why they couldn’t ask the cops to come back without their guns or leave altogether just because there isn’t a sign.
Number one rule if you carry a gun for a living. Don't give up your gun to anyone or for anyone unless it is to a superior officer or LEO who is acting in the line of duty!!!!!!!!!!!!!!!!! Cops do not give up their weapons because some tree hugging, anti gun moron thinks they should. Even in a court room where everyone is screened on the way in the bailiffs and cops who are there to testify are armed.
To ask them to do this is asking them to violate department policy and any and all common since, rational thought and logic. I can clearly see that you have never been involved in a job that included carrying a firearm.
I still don't get why anyone would think it is OK to ask a cop to give up their sidearms. To me that is one of the stupidest requests on the face of this earth. That is like asking a fireman to please not keep water in their firetrucks or paramedics to please not keep medical equipment in their ambulance. Dumb dumb dumb