The board of trustees are apostles, general authorities, general auxiliary presidency members, and the like. They care more about the mission of the Church than winning football games. They see opposing coaches and AD's praising Kalani (and TH) for their character. They see opposing fans and press praising the BYU game experience and fanbase. They have to be pinching themselves about how good the sports programs at BYU are doing from the standpoint of building bridges with other good people. If you wanted a head coach who presents as an unapologetic disciple of Jesus Christ, you could not design one better than Kalani.
Also, he's 4-0.