It would be easier if I could draw a diagram, but here's why it's still a T.Rex. Imagine you're wearing a shirt with very long sleeves, so long that they extend well beyond your hands. That's basically what's going on here. The T.Rex that is Hugo is wearing this human outfit, but since his arms don't reach the full way he can't grab anything except something really close to him. However, if he flails his arms, his arms then smack something further away because his stubby actual arms are flailing the outfit and the outfit is smacking them.