I just watched this part and this is so infuriating to me. They are such horrible, awful parents. They actually blame Disney for having the audacity to put a slide in a well-trafficked area that their precious little genius can't ride.
I also watched the part where he had to prove he was right about the number of elevators. Gin was actually kind of rude to one of the Stans and said he was wrong and Dim was right. Then Dim has to prove himself right and looks it up and lo and behold there are actually more elevators on Wish. Oh, but Dim really meant less banks of elevators. So HA! Stan they showed you! Dim always has to be right. Which to me also shows a lot about their character. They are always insisting they are right or making excuses. Assholes.