Kairi pillow indeed! She ruffled Sora's hair and began pretending to braid it. Because could you really braid Sora's hair? Ever? "Don't call it primping! That's too girly." And Riku was not girly looking, inspite of his long hair. There was no way that body could be mistaken for something female.
"Really, though. Its just us. He doesn't need to look... groomed, for us." They'd seen all stages of Riku hair, including bed-head. It really didn't matter.