No, papal infallibility is modernist for relativism. Truth does not depend on authority. To-say-so is a logical fallacy. Truth needs evidence, not just pristine-reason. Especially on sex. Relativism is to say there is some kind of unique Catholic sexuality, which in truth are a collection of neoplatonic arguments that have been disproven by science. Morality is for the good of people, not of God. Saying otherwise does not serve God but makes him look like an Ogre and a Fool, and God is neither of those things, but many clergy are both.