I wonder if the owner could have the thugs arrested for trespassing, and then sue them for loss of revenue.
The decision to charge with trespassing is up to the DA, although the property owner usually has to agree to proceeding with the charge. I think the owner has the right to obtain restraining orders forbidding any of the people who disrupted the place, from returning. I'd do at least that. Separate from obtaining a restraining order, he can certainly sue them for loss of revenue. Damages aren't much, probably, but defending the suit is a thorn in the side of the juvenile-acting disruptors.
I found it interesting that the instigating woman, Moran, is married to "a top researcher at the Ohio Republican Party."