I agree with your premise but you have missed mine. Homosexuality is not a condition. It is an activity. One cannot be a homosexual unless one has engaged in homosexual acts.
The Catholic church disagrees with yout premise. They do not take the position that “homosexuality” is only a behavior. It’s just that the Catholic church condems all sexual behavior outside of marriage, and marriage is only the marriage of one man and one woman. EVERYONE outside of marriage is to remain chaste, if they are a faithful Catholic.