It's possible the gun show organizers admit the beanie baby vendors (are we now lumping all non-firearms-related vendors into a single category with this moniker?) because they don't have enough firearms-related vendors to fill the arena. Possibly also they have firm commitments from the BB vendors while some of the firearms vendors hem and haw about setting up at a show? Just spit-balling here.
It's not only possible, I'm sure that's true. That doesn't change the fact that it's still up to them to allow (or not allow) beanie babies to be sold at their event.
They don't help themselves when the same promoter schedules shows in OKC and Tulsa on the same weekend either. I know some vendors who setup at every RK show and they have reserved tables at each location. They were left scrambling trying to figure out how to keep their table locations and which show to attend.