The answer is:
He wants to show that the pigs have become identical to the human farmers, just as Stalin and other communists became like the aristocrats they replaced.
In chapter ten of "Animal Farm," the author George Orwell makes reference to the transformation of the pigs, from communist revolutionists to aristocrat totalitarian dictators. In the end of the story, Napoleon tells the farmers that Animal Farm will return to its original name - Manor House, which exposes the pigs' wish to become as oppressive as the human farmers they once rebelled.