You are correct sir. But... All that gets thrown out the window (unfortunately) when you enter onto private property run by a private club. He broke no laws, that is not in dispute. The dispute lies in that there is not "official" policy with the Washington Arms Collectors regarding legal carrying of firearms by assosiate members (members between the ages of 18-20 years old).
We all want this to change so that he will be able to carry while at the gunshow, according to gunshow rules (properly zip-tied)