Thoughts are simple. OKEx Korea know everyone on their exchange, since they KYCed themself. So they know who deposited every coin on the exchange as who withdraw coins from that exchange. That is what FATF policy is all about. In FATF policy there is no reason for delisting any coin. There are just reasons for them to focus more in KYCing their customers.
Make sense, that's why Okex Korea delisting this privacy coins and not only OKEX korea are working on this. I've heard a news regarding the same thing, delisting privacy coins in upbit korea. Looks like korea are strict in their law that's why exchange have to comply with this or they will be in a huge trouble.