Bans like this are straight silly. How exactly do we propose to stop anyone from carrying? Maybe some TSA style security theater? We going to scan thousands of people coming into fairgrounds?
Now people like me will obey the law, and some will not. Now I am unarmed, and they are. People planing mayhem, or people who prone to it, will simply ignore this. And in some states, it’s perfectly legal to carry on private property even if the owners ban it, you can only be forced to leave under threat of trespass. In others, you’re going to jail if caught.
Being a gun nut, I’m leaning towards the latter. If a property owner says, “No.” (to anything), I’m inclined to side with them.