I think it's a little rich that Snowden is complaining about being labelled a traitor - morality aside, what he did seems like a pretty clear-cut case of treason from a legal standpoint (IANAL).
"Being called a traitor by Dick Cheney is the highest honor you can give an American"
Although, I don't know what the laws are like in the States, but in Canada you can go to jail if you have security clearance and reveal information that if true would be classified. If the legal situation is similar in the US, he's pretty clearly guilty.
Now if he turns around and starts helping China with the information he has, then he will be pretty much done for.
From someone who is a lawyer:
“I do not believe it is treason,” said George Washington University law professor Jonathan Turley. “There is nothing to suggest that his motivation was to assist our enemies or a foreign power.”
The gist of the article is that they would most likely prosecute him for espionage (which doesn't require him to be spying "for" anybody), and that the treason/traitor allegations by officials are for rhetorical effect (though they mention it isn't entirely impossible to charge him with treason using some very tortured logic).