In any event, employee compensation clawbacks generally are only available for losses that were incurred prior to the payment of the compensation. The idea is that someone who misrepresents the profitability of a business shouldn't benefit from their misconduct by getting a bonus based on the inflated profits. Nothing like that seems to have happened in this case. In many countries (including the United States) you don't have to prove the employee was at fault. It's sufficient to show that the bonus was paid based on incorrect information.
As far as a non-employee clawback goes, generally you can't clawback funds from someone who gave something of comparable value for the funds received unless you can show wrongdoing on their part or the contract specifically permitted a clawback. It's very unlikely that ZhouTong's contract would have permitted a clawback for anything other than a materially significant misrepresentation or omission on his part. And there's no evidence so far, at least as I know, that ZhouTong did anything like that.
Tort law doesn't work that way. Prior principals can be liable, and there is a mountain of case law in common law jurisdictions where this is the case. If full payout was not returned to deposit holders, then there may be liability due to negligence from a lack of due diligence with the buyer / current owner of Bitcoinica. Further, as you implied, if the seller received compensation significantly higher than the true NPV/MTM of the equity, the difference may likely be subject to legal claims even if Zhoutong acted in good faith if the current owners convinced Zhoutong to sell his company so the current owners can strip/steal all the deposits (as the non-disclosure of the ownership transfer was proximate cause for the loss).
It is in Zhoutong's personal best interests to ensure that Bitcoinica client funds are returned in full if he is not colluding with the present owners, otherwise there will be significant economic incentives for deposit holders to investigate the identity of Zhoutong and all parties involved.