I'd understand if they were doing some long ride but around center parc can't be more than a couple of miles. We've been camping in some popular cycle touring places on the continent recently and there were whole families cycle touring, with some very young kids riding their own bikes with luggage attached, and very happy doing so. She makes him such a baby, and also lazy in doing so. I take it he's not into football like the older two either so not getting a lot of activity perhaps? He was also really late to swim without aids wasn't he? For which she blamed covid, but plenty other kids have managed.