Some users who took advantage of the bug and withdrew funds to their bank accounts found their accounts frozen shortly after, when Coinbase noticed the error and began working to claw back the funds.
Typical... and it's not the first time I see this happen. Usually exchanges freeze the customers accounts until they return what they earn on those trades. It's a bit shady... but it's probably covered in the small print in the TOS they have.
Even if they don't freeze your account because you cleaned it out and don't plan to use it again, you're using a KYC service, so they have all the details they need to come after you and the money to nail you legally