We have stayed there several times and never had anything taken. It is a nice campground, clean, friendly staff. Funny, I have wondered about the same question at times. If your tent disappeared that would be a massive inconvenience to replace. I did wonder about back country sites if you are leaving expensive backpacking air mats and sleeping bags unsupervised.
In all the years we camped we only had our stove stolen once in a national park car campground - a good record, I think. Oh, and we had our hubcaps stolen once at a motel en route! Now we leave the Porsche at home.