Infallible?

David Bokovoy advises that we should

Remind youth … that [Church] leaders have made mistakes in the past and that if  [liberal Mormons are] correct, that supporting same-sex marriages is the correct moral path, then the Church will eventually make changes similar to those related to the Priesthood ban. 

Of course, I don’t believe Church leaders are infallible.  But there are two different approaches to prophetic fallibility.  The conservative approach is that they might be mistaken about some things, the liberal approach is that they can be mistaken about anything and everything.  In a sense, secular autonomy insists that each person should choose for himself which commandments they want to follow.

But Bokovoy’s claim here raises a question.  If we teach our youth that Church leaders are mistaken about homosexual marriage, why should our youth not suspect that they are also mistaken about teen sex, premarital sex, or marital infidelity.  The secular sexual revolution is not just about homosexuality, it is about human sexuality in all its intricacies.  If the Church leaders are wrong about homosexual marriage, as David believes, why should teenagers think they are right about sex outside of marriage?