Copyright doesn’t extend to a title, and besides, the Book of Mormon is way old enough to be public domain.
Of course you’re right, I’m just thinking that the Church of LDS Inc. has the legal horsepower to sue the pants off anyone who “misuses” the term Mormon, especially if the target’s located in Utah or the intermountain corridor.
If I look up the status of that application at the United States Patent and Trademark Office, it appears the application was abandoned on August 22, 2007.