How, according to Goldstein is the ruler of a place like Oceania greater than a pharaoh or a caesar?

The rulers of Oceania are absolute. No force will ever threaten their perennial power. Leaders like Caesar or the Pharaoh’s of Egypt were not perennial. They were constantly threatened. Indeed, even if Inner party leaders like O'Brien died, the ideology of the party will remain unchanged forever. This cannot be said of ancient rulers.