Maybe they thought he was special needs and they didn’t want to draw any attention to the fact that he looked so out of place. It was the most logical conclusion he could come up with, it made him feel slightly guilty knowing that he had a sound mind and they might of thought otherwise when other people truly did suffer from these conditions.
But many of them would have seen him when they first arrived, seen him pulling down on his t-shirt in a vain attempt to cover his pull ups. They would have witnessed his decline into now being walked around in nothing but a diaper. So they had to know that wasn’t the case, was their some magic field around him that when people looked they saw nothing but a toddler or little boy.