By virtue of the fact that he's employed in a Catholic church, your church's music director isn't a Mormon, he's an ex-Mormon, which means he's just as anathema to practicing Mormons as anyone who's not Mormon by birth. No practicing Mormon in good standing with the Mormon church would ever be caught dead working in any other religion without facing severe reprimand, most notably excommunication. Perhaps it's fair to say that your music director's treatment at the hands of his own church (probably being kicked out for being gay since there's a fairly large percentage of gay church musicians) has led him to be more compassionate towards others. That would be my bet. But's let's be clear: he is not, repeat not, a practicing Mormon if he's working in a Catholic Church. If he is, he's doing it on the down low.