Why would Charlo do this though? He has money now, he doesn't need or want a beating, even if he won a decision.
It's not that important to him.
Ultimately after getting undisputed + being early 30s Mell was seeking money fights which Tim isnt. Tim is a high risk low reward. They should have done this fight in the USA to boost Tim more for a Mell/Bud/Spence future fight