Pouf tells Knuckle at once that the body he sees is only a shell — his core is already making for the King. He assumed Knuckle learned the ability from Morel, and Knuckle confirms it for Gon's sake, asking why he mentioned it. Pouf's mind lingers on Youpi: the fact that Knuckle is alive means Youpi allowed him to leave — the permission was the guard's.