As I understand the setup, I don’t see any possibility of this happening.
If BYU wins the Big12 CCG, they will be a top 4 seed. If they lose the CCG, I don’t see a path to the committee seeding them 5-8 to host a playoff game.
If the Big12 happens to get two teams in the playoff (not sure this happens), the second team will surely be seeded 9-12 and play a road game.