Your FMV definition here is overly narrow. It isn't just what someone is willing to pay for services rendered especially when paid by a compulsive booster.
FMV is most commonly used by banking and insurance firms to determine the value of assets to be used as collateral and insurance. The government also uses FMV for taxation and eminent domain where they need a value for an asset. And the IRS uses FMV for charitable donations and other transactions, meaning deals between related parties. The Clearinghouse will apply similar FMV standards in distinguishing pay for play vs True NIL with extra focus on deals registered by athletes with booster businesses.
And to say there is no legislative appetite for an anti-trust exemption and codification of House is inaccurate given
the volume of recent bi-partisan US Senate activity that has been reported.