No, I have not been to that specific gun show. Between common sense and insurance requirements, there is bound to be signs posted there. Convention Centers do NOT like negative publicity or liabilities. These people could sue the building owners which leads to another scenario. Was it staged for the insurance? It is unfathomable in my mind it was not posted “No Loaded Firearms”.
I'm not saying it wasn't, but is it unfathomable that the person could be funneled into the entrance area BEFORE any such posting could be seen, and thus "forced" into the challenge from a guard?