He's in direct contact with the client. I'd just explain that he can't (not won't) continue to work on the project because Freelancer effectively stole the clie

He's in direct contact with the client. I'd just explain that he can't (not won't) continue to work on the project because Freelancer effectively stole the client's money. I'll bet if he's doing as well for them as he indicates, the client will hire him outside of freelancer. It may violate some TOS, but I'd call that bridge burned already anyway.