The Holy Father could be wrong on prudential matters, and I don't think his argument stands against those of St. Augustine and St. Thomas, or the different opinion of the present pope.
The hidden rationale is the same: I am a liberal or conservative or Republican or Democrat before I am a Christian.
The bottom line is also the same: I am the Supreme Authority over what I will and will not believe, and if the Church doesn't like it, the Church can stick it!