I am not so sure. He believes the Catholic teaching on homosexuality is in error - in disagreement with the "true" teachings of Christ.
And that's just one of any number of Protestant views. Who censored cares what Protestants think that Jesus taught? There's only one college of people whose view is of any more significance than the livestock's, and that's the Magisterium's view, as you already know! Why are you sloshing around in the muck with people who don't believe that the Lord Jesus was kind enough to ensure that His flock would be shepherded consistently from His Ascension until His Second Coming? There is a level beyond which, they're just not walking with you anymore, and you're on your own as a Catholic who believes that the papacy and the bishops in communion with the pope, are the One Church's true teaching office. They want to cling to their own opinions and clever spins on Sacred Scripture; they don't want to know the truth, and they don't care what you say, and you're selling your faith short in stooping to their level.
They're simply wrong, and they simply won't hear that they're wrong. That's not an option for them; that they're wrong. You're so much better than they are.
So pulverize their thinking. Grind it into pulp. They are so arrogant as to think that the Lord wasn't capable of maintaining His "visible" Church much past (fill in the blank here, everybody acknowledges that the Acts Church was legit, different Protestant-types say that it went wrong before the end of the first century, some with Constantine, some with the East-West Schism of 1054, some with the Reformation, etc.) some point in history, and from then on, His Church either became "invisible," or else some other "visible" ecclesial community grabbed the baton.
Funny that it's never Peter's baton. Not a single one of these other candidates for the Lord's Church that He actually built (as He said He'd build) makes Peter prominent like the Catholic Church, even though there's that verse, where Jesus promises that His Church will be built upon Peter! And hundreds of millions of Christians fall for it! "You are Peter and upon [you] I will build My Church," He said!
So they don't believe the Bible either. They'll swear up and down that they treat the Bible as Catholics treat the moral and doctrinal authority of the Magisterium, but they don't really. They just believe whatever they want. So don't bother going down the rabbit trails, just argue who you are, where you come from, because they're not going to change their mind anyway. And the biblical case for the Catholic Church is far stronger than any other case on any other matter of faith and morals that you could make.
"I will build My Church upon this Peter." "This Peter" means "pope(s)."