Because you can't ban HedgeFX if there are still numerous other cases, where the evidence is completely clear, that these Accounts committed Plagiarism. If you ban HedgeFX now but don't ban the open cases of first offener Accounts, that's completely inconsistent. Especially considering that ban evading has been enforced pretty arbitrarily recently. Maybe that rule is inactive for now as getting an Account banned once is punishment enough for most cases.