Well if it perfect zecter maybe it can defeat satan sword also even without clock-up Kabuto usually fight with confident even with who the opponent are and always win easily. Shadowmoon maybe strong but if they have a fight then Kabuto might win somehow because he's smarter. Beside creation king created the stone and native created the zecter and it seem the universe have more life then you thought. Kabuto gain power from zecter but Shadowmoon fused with his power so if his power die out he die too.