Think about it. The Punkin King is unable to be damaged by our weapons until he chooses to trick any knights who wander into his domain, rather than treat. We can't hurt him unless he says so.
Even then, no one has truly ever "defeated" the Punkin King, no matter how powerful their armor and weapons. Vanaduke, Roarmulus, the Royal Jelly, and all their Shadow Lair counterparts have fallen to our might, but the Punkin King still walks, haunting the Clockwork Tunnels and handing out candy to any groups of knights who come across him.
Haven still exists and we still live merely because the Punkin King has no desire to destroy us.
He must be king of King Tinkinzar