The new multi-year contracts the P5 have with their bowls requires the bowls to accept team provided by the conference. The bowls do not have the freedom to choose a team from outside the contracted conference, unless the conference doesn't have enough bowl-eligible team.

The Vegas and Hawaii bowls slots became available because the MWC (which has a 6-year contract with both) wanted a one-year opt-out option so it could go to other bowls.

Unfortunately, BYU is not ND. Conference teams can schedule as many games they want without the conference granting access to its bowl lineup.