It is not that common, but also not unique, to require all arrivals and depatures to be escorted.
I think the assumption of being toadless means you will be going in and out is unreasonable. Many parks emphasize ready access to public transportation and no need for a toad. But maybe the owner knows that is not the case there.
As with so many arbitrary criteria (vehicle age, entertainment animals, RV type, number of occupants per site, self containment, no camping) the operator's option is to make rules, your option is to go elsewhere.