It’s hard to assess the actual risk: cartels haven’t necessarily been associated with cryptographers, but Silk Road made a connexion, and home-made submarines have proven a track record of adopting innovation fast and efficiently.
The sliver of risk, no mater how thin, seems not worthy of openly naming the person, as opposed to offering close-up photo and a third party confirmation that the details appear consistent.
It's also the wrong guy by the way.
In the words of Lebowski: It's not wrong, it's being an asshole.
Being an asshole =/= unethical. Make a real argument that it's unethical.
Journalists are in the business of finding out information that's useful for an open democratic society in making decisions. If this person might be the genuine Satoshi, then it stands to reason he might offer useful information or a new perspective on Bitcoin or money in general.
Thus I think to not pursue this story as a journalist would be a violation of j-ethics.
The real reason behind this fear is that some consider Satoshi their hero and icon. Anything, therefore, that he doesn't or wouldn't (if you maintain this isn't the real Satoshi) approve of especially as it relates to himself inspires strong feelings and irrational justifications like "he could be kidnapped and tortured."
Or at least that's the only reason I can imagine this argument keeps coming up. Any other wealthy person could also be kidnapped and tortured. Heck, most wealthy (100m+) people probably have pretty valuable things just laying around their house that are far less traceable than Bitcoins.
Of course, in this case, I hope the bitcoin network would resign itself to coloring those coins, if Satoshi was extorted out of his coins.
I agree there's (hopefully) a good chance his BTC are in cold storage in a safety deposit box, or something. People fail to do that with BTC more often than people fail to put millions of USD in the bank, though.
Actually, I've been wondering if he didn't withdraw from BTC because he was embarrassed about having lost the private keys to his early accounts... :-P Not that I really think that likely, either.