When a group of bowls and a group of conferences collude with each other to create a cartel, the possibility of anti-competitive behavior emerges. There's no question that a cartel exists, the only question is at what point the benefits of threatened or actual legal action outweigh the benefits of going along and taking the bribe money. For BYU, saber rattling by friendly politicians may be an attractive option *if* BYU were to get stiffed in 1996-like fashion for a major bowl. But that hasn't happened yet, and it's plausible that a highly ranked BYU would be selected for a better bowl than it could have negotiated in a free bowl market.
If the cartel started playing itself exclusively and formally cut all non-cartel teams out of access to the playoff and playoff-hosting bowls, I think you would certainly see antitrust lawsuits from non-cartel schools, BYU included. But I don't think that outcome is at all likely.