A bizarre play by Snowden, who seems to have gone to Hong Kong in order to be in the strange space that currently exists between the US and China right now, where despite the normal standard of extradition from HK to the US, there exists the possibility of a Chinese veto. Here, I think Snowden is primarily stalling for time, saying that if China helps his cause (i.e. not allowing him to be extradited) he might do something that helps China.

I don't really know how I feel about this either ethically or as a strategy, but it certainly could play out to Snowden's personal advantage after a bit of time on the international stage. I'd imagine some pretty senior level guys will get involved, and they will decide what to do with Snowden.

That said, regardless of his ultimate fate, this does seem like a legitimate and probably successful tactic for him to buy himself a bit more time in Hong Kong. The Chinese government will probably want to know what he knows, but they will presumably also have to wait for him to reveal what he is willing to over time.

Keep in mind Snowden has already hinted he knows some pretty "dirty secrets" and given his crypto background, etc. it is possible he has some sort of other treasure trove of documents that he hasn't handed over to the reporters yet -- this is sort of an ugly and dangerous game, but I'm sure he knew that from the moment he set things in motion.