Actually there would be no one alive for him to rule to world. He would be a country less king. /
To make it clearer, he would be king of absolutely nothing. So he's useless! Muhahahaha!
On a side note, I imagine him coming out from below a rock (Like Patrick) and take out a golden plated staff (Which he kept with him during the WW III) and raise it high above his head as he come out from below the rock claiming "I've finally appeared and I'm here to rule the world! Nothing shall stop me! MUHAHAHAHA!" Just as he finished the sentence, a rock the size of a... well, rock hit his head and he looked up. It is raining Rocks!