This is why I've been an owner for years now - the mail to revert back never arrived.
As I said, CS should help you, not only tell the obvious. IT would also be nice to get some more support by the mods.
You might check with your mate if he usually receives WGT mails, tournament messages, account confirmations like "you bought...", "you received a gift...", "you won ... credits".
If so, he might want to check his mail bin, spam device (quickly before it's emptied).
If not, guesswork begins. He might change in his account to another of his personal mail addresses and try if the mails arrive there. He might also leave and rejoin the CC.
You might then invite him to ownership once more.