Kewne has the ability Unbrainwashable. Later in the story, when you get to the top and meet Beldo, he's forced to comply with his master. When Beldo is about to kill Koh, Kewne seperates from him, showing that he was never really under Beldo's control, just waiting for a moment there would be someone to take him out!
While it's true Koh wanted to go into the tower partially because he wanted to find out the fate of his father, what if he never went up to the top floor? Considering most people seem to only make it to the first few floors, would he be stuck there forever?
At one point, Selfi is being attacked by a Pulunpa, but it looks like it's... doing something else to her. Later on, she gives you a Pulunpa Egg...