I am bit surprised that you a make such a big issue for Joshua to travel to Russia. As if Brittain is not corrupted in terms of judging and drug testing.
Povetkin was cheated by Haymon and the WBC before, they deserve a fight in Russia. Ryabinskiy won a lawsuit against Wilder, could force Wilder into a fight, as Povetkin was cleared by VADA, yet Haymon's WBC refused to allow Povetkin to knock Wilder out! Yes, they won their suit!
I don’t think they are protected because they haven’t travelled. I think they should travel if they lose a purse bid though. Problem with your analogy is mayweather never lost a purse bid, sure if he lost the purse bid and vacated then he should of travelled and I think his legacy would be even better if he travelled.