THe governing bodies don't overrule a contract. They can strip the beltholder for not being able to comply, but that's it. He's worth a lot less without his belts, certainly when they're in Haymon's hands. Do you think he will just ignore the contract and be sued blind? Those tens of milions (not hundreds, be real here) are worth nothing if they have to pay Hearn and Joshua damages. Please stop believing you can just breach a contract and get away with it. Why wouldn't it? Unlikely that they just would let Haymon do his thing and then let the winner of Ruiz vs Wilder hold the belts hostage for forever. That's just ridiculous.
If mandatories are called then it's not a case of a contract overruling it or the other way around. Ruiz will have a choice: Rematch and lose a belt or refuse the rematch and face being sued.
Has there been any examples in history where the immediate rematch clause is shown to mean to include mandatory defences. Because Hearn could be shooting himself in the foot otherwise. If as you state immediate rematch includes, that the new champion, cannot take a mandatory defence, them that new champion has one viable option, which is to drop the belt. Then Hearn has shot himself in the foot by stating such an unworkable clause. It's not ruiz fault if the wbo or ibf call a mandatory to take place before the nov/Dec date given by Hearn. If they do then all ruiz can do is say sorry guys I can't fight you cos I have a contract with Hearn which says I have an immediate rematch clause with a.j and immediate rematch covers a mandatory defence. I cannot fight my mandatory because I have a contract with Hearn and I can't fight my rematch because the governing body has ordered my mandatory, I only have one option which is drop the Yes I agree.
To be fair to Pulev he has been waiting on his IBF Title shot since October of last year- I imagine that he’s accommodated with the first shot at the winner of Joshua/Ruiz in early 2020.
a private contract is nothing to do with the boxing establishment or titles, Ruiz can do what he wants but could lose money in court and belts if it drags on and he doesn't fulfill their requirements. Point is they cannot make him rematch Joshua and even a stripped ruiz v wilder is a legit fight , belts value will not mean anything if taken away