What is confusing about his motivations? Nothing has been suspicious about the revelations he has made thus far or in his stated intent. The only thing slightly suspicious is that he chose Hong Kong, but there are many explanations for how it's a reasonable choice (The asylum application process is currently being reworked and he likely can't be extradited before that's complete, it's a major media capital from which he can engage with the story, it has one of the few governments that is in a position to stand up to the U.S. and that could cause major implications if anything fishy happened...)
I think this differs very little from the other revelations.
This does make the government look bad in the eyes of US citizens--why are we crying foul at China when we are doing exactly the same thing, and may even be the more aggressive party?
If we are conducting this sort of warfare, the citizenry needs to know. It's probably a better issue to face publicly than to let it slowly morph into a new cold war espionage situation with China.
I don't think he has given any information from one country to another.
He has revealed to the American people that they are taking an offensive rather than merely defensive role in a hacking war with China. This is important for the American people to know--how can anyone come to a reasonable conclusion about the issue if they only hear the government line that China is hacking and the U.S. is just defending?
China has also received this information, but it's ridiculous to believe they didn't already know there were hacking attempts.
He has not at all signaled, so far, that he would like any special consideration from China. He has not claimed to have "a lot of info" on US cyber attacks on China. He has said he would let Hong Kong decide whether he deserves protection from extradition.
He has said the U.S. is cyber-attacking China. This is important information for the U.S. public to know when the U.S. government is criticizing China for cyber attacks. How can people hold the executive branch accountable when they're basically being lied to? ("The Chinese are cyber-attacking us, and we only defend...") Is there a primary aggressor in the cyber war? It's an important question.
Suggesting he is a spy for revealing very non-specific information that the Chinese government already knows but the American people do not is ridiculous.
How is he advertising such a thing? He specifically said he carefully chose documents that would be in the public interest and not documents that would be a threat to national security.
If he did indeed reveal this, how is it "buying favor from the Chinese government"? It's hard to imagine the government of China doesn't already know about these attacks.
The beneficiary of this information is the U.S. public, so they can actually have a real discussion about cyber warfare, rather than simply believing the government line of "China hacks us, and we only defend...". How can we have a real discussion about our role in the world if we're told only about foreign aggression and not our own?
Could you please offer citation?