First, no excuse for a campground owner or host to be nasty. This is a customer service business and at least an offer of another site, an expression of concern or a partial refund is in order here.
Having said that, we have rated parks using the GS criteria in our travel directory. We've always come out within one point of the ratings in the book. The rating system is objective and points are scored for grass, swimming pool, level sites, etc. I looked at the site on Google Earth and see why you would be concerned about a large rig on the pull-through sites since they are very close to the road.t But there's no place to rate a site on a curve or a nasty host or owner.
While the OP feels the CG is rated too high, we've stayed at some we feel are rated too low.