His public disclosure makes that exceedingly unlikely. At this point, China would rather let Obama reap the shitstorm alone.

Exactly, China doing nothing is a free PR win for them because they look tolerant while the US is clearly attempting to close down discussion.

I think he made one of the best choices he could but, as he says, he can't ensure his own safety anywhere really.

What China could hope to get in intelligence far outweighs PR. They laugh through PR controversies.

China has been engaged in massive cyber espionage themselves. Everyone knows it, but no one can prove it beyond a shadow of a doubt, so they keep denying it, and nothing of consequence happens.

They could whisk Snowden off to a secret interrogation site, and then blame the CIA and say the US government snatched him. Who is the media going to believe and who can prove otherwise?