No. What they did is unprofessional, completely irresponsible (they didn't even contact the person they are claiming did something wrong--- so what is the point of the thread?), and possibly illegal.
Unlike many of the people on this forum, we act based on legal advice from seasoned lawyers.
The information disclosed here has been disclosed for some time to the people involved with Bitcoinica, but it seems that none of them has talked to Zhou about this yet, nor started any legal action (at least none that reached any of us).
No legal action = you have no right to disclose it publicly.
While I'm sure we're all eager to hear Zhou Tong's response as it is unfortunate how the situation looks, it is unnecessary to make this a forum witch hunt and is becoming more and more clear that you, AurumXChange and BitInstant do not take your own privacy policies seriously.
Hold the funds privately, let Zhou Tong give up his own right to privacy by bitching about it on the forum if he chooses to, but don't go breaking laws and giving out your customer's personal information to angry internet mobs and endangering his life when you don't even have sufficient proof that he is actually anything more than a victim of identity theft. This disgusts me deeply. The Zhou hating is tolerable from this community, but if you have any sense Mark, you will remove yourself from this thread that AurumXChange seems to be only so happy to risk their entire business in posting.