Leaving the MWC was also posturing for BYU, being more "available" and "less G5" when it came time for P5 league expansions. And it came close to paying off in 2016 when BYU was one of the 12 finalists for Big-12 expansion, and Boise St, SDSU, and UNLV were not (CSU and Air Force were). But the Big-12 decided that none of the finalists were worth adding.
That was 2016. Since then #MeToo happened, and then #BlackLivesMatter happened. And in the 2020's no school named after an openly racist polygamist with 50+ wives is going to be invited to a P5 conference without a lot of pushback over renaming the university.