This is possible. Even if Zhoutong received a fair price, he could still theoretically be held liable for negligently transferring control over the assets of his depositors.
From the facts known to me, this seems like an extremely unlikely way for events to turn. It seems, at least to me, that Zhoutong negotiated in good faith, believed the people he were dealing with were more competent than him to run the business, and had no reason to suspect any of the future problems. I don't know whether his compensation was fair or not, but I understand he was motivated to sell, so it's unlikely he was paid more than the business was worth.
It doesn't matter. I'm not talking about theoreticals, the facts you and I know regarding the ownership transfer is slim-to-none and that's one of the fundamental problems. To postulate that he was not paid more than what the company was worth is indicative of
illusory self-confidence in knowledge, unless you are privy to non-public facts that have not been disclosed here (if so, I'm sure people that have lost money would love to know).
If I did not make it clear enough, the lack of public knowledge of ownership transfer creates serious potential for negligence claims against Zhoutong (as he has a fiduciary duty to deposit holders). Transfer of a money service to another entity which has
different credit risk/security expertise without disclosure, then having the new entity defaulting on debts is an open and shut case of proximate cause, I disagree with the opinion that it's an unlikely avenue of pursuit in the event of actual default.
To reiterate, assuming that Zhoutong has zero involvement with the theft/loss-of-funds, it is in his personal best interests to ensure/advocate that everyone gets paid back in full.