I don't think that it should be up to the promoters to do as that just seems like a terrible system with yet another bit of power going to the promoter but the athletic commissions already have a system of punishment in place where fighters can be fined and the money goes to the opponent for missing weight. It seems logical that they would do something similar for PED failures on fight night. Even if they split the fine with the clean fighter it would make more sense then the shady commissions getting all of it.