The main answer is that the bowls are independent of the NCAA, the governing board of the athletics. These bowls can independently determine how they want to fill their games. The playoff and NY 6 bowls have determined to let the playoff committee select teams for the playoff and the outstanding spots in the bowls if the teams contracted to certain games (ie Big 10 and Pac 10 to Rose, SEC and Big 12 to the bowl in Dallas, ACC to Orange, etc) are included in the playoff.

Another reason why the anti-trust case goes out the window is the G5 conferences all agreed to this as well.

The one thing BYU (and Army and Navy) could hold over the NCAA is that they were not represented by a conference and were not able to officially give input, while Notre Dame who is an independent did have input.

This year is actually a good year for BYU with regard to access, as there are potentially 6 (more likely 5) at large slots. In future years, when the Rose/Dallas bowl aren't hosting playoff games, the at large slots in the NY6 could be as limited as only one.

If BYU goes undefeated, they will be ranked in the top 10. If they are ranked in the top 10 of the playoff committee polls. If that is the case, they will get one of the at large births based on the principles of the selection committee.

The committee will select the 4 playoff teams, place the remaining P5 champions not included in the playoff, place the G5 team (if not included in the playoff), and then place the at-large teams just going by their rankings. If BYU is the highest ranked at large team, they are in. This year, they could be in being the 3rd at large team (including all the conferences).