Purpose of U.S. Power in Latin America

The National Interest asked various people what the purpose of U.S. power was. John Mearsheimer's answer left me shaking my head in frustration:

There is one meaningful threat to the United States: the appearance of a potential hegemon in Asia or Europe. The purpose of American power should be to ensure that the United States remains a hegemon in the Western Hemisphere, and that there is no regional hegemon in Eurasia. This rationale led the United States to help prevent Imperial Germany, Imperial Japan, Nazi Germany and the Soviet Union from becoming regional hegemons in the twentieth century, and it remains relevant today.

First of all, it is inconceivable that the U.S. would cease to be "a hegemon" in the Western Hemisphere, so it's weird to claim this as a goal. I don't know if he means to suggest there could be several hegemons, but my hunch is no.

Instead, I take this to mean the U.S. dominates Latin America to keep out Russia, China and Iran. He does not mention that the Bush administration's obsessively efforts to do so actually pushed many Latin American governments even closer to those countries. U.S. blundering in the name of hegemony has caused all kinds of problems.

More troubling is that his example of keeping out the Soviet Union meant killing or encouraging the killing of countless people in Latin America. It included accepting the worst type of venality in the name of realism. It was shameful and contrary to what the U.S. claims to stand for. After all we learned about the Cold War, this is what U.S. power is for? I hope not.