Well there's no need for the king to eat someone if his arms' just lying there waiting to be stitched. Pouf made a ditch effort that may or may not have worked. It banked on the idea that when the king eats he "absorbs someone's power for himself". I think the guards were mostly afraid the king was going to die from blood loss the time he chopped off his arm, not that he couldn't regenerate it himself.
The point of that scene was that he was offering his arm as a sign of his disrespect. The conceded when the guards cried to repair him.
I'm rather glad Pouf is still scheming. It keeps things interesting because I don't know what else will, really. That said, the beginning of the episode was pretty hilarious.