I really wish he’d said “ought” rather than “must.”
“I really wish hed said ought rather than must.”
Catholics and Protestants have been telling each other what do for quite some time, and probably will for quite some time in the future.
Really though, the Pope does have a dog in this fight as too many of his flock (at least in the US) actually are closer to Protestants in how they actually live. So if they are going to act like Protestants, he should have some say.