I can't see an "in-game bank" providing any more security than is already in place. The hacker is already in your account and has all the same rights you do to withdraw money from the bank.

If there was any mechanism that might provide better protection, it would probably be requiring a second approval for FC withdrawals - but even that would be vulnerable to the hacker-controlling-your-character inviting another character under their control to the FC, promoting them to have approval rights.