Absolutely NOT.......
Show me the law that states that. As far as I read when a private entity signs a permit to exclusively use city property they become a leaser and have full control of the property listed in the permit. For example: Normally you could not openly consume alcohol, nor sell it, at riverpark west. However, this is the sight of Oktoberfest Tulsa, and the amount of beer sold in those 4 days dwarfs what a bar or two sell year round. At that point Linde Oktoberfest leases the park and is allowed to write their own rules.
Any other time these yahoo's walked that area with no event going on, yes they have every right to carry legal pistols. However, at that particular point and time it was leased city property and the event management has the right to set the rules to attend that event, even if its free and open to the public.
So please, provide legal proof of your statement. If I believed everyone on the interwebs I would stop paying my taxes, take the tags off my car and shred my driver's license.