BYU needs to play as many games as they can. Pure and simple. 12-0 looks a heck of a lot better than 10-0. Each week they are idle (the next 2) will hurt BYU more than 2 games scheduled against teams from better conferences than the ones they’ve been playing against.
Based on what you’re saying BYU needs to limit who they play based on who’s in front of them, but why would those teams be willing to play us? That’s not going to happen, so fill up the schedule.