From the NYT article: "The data, if independently verified, could help Chinese officials figure out which computers have been hacked, patch security holes, itemize compromised data, analyze the quality of computer security defenses and develop techniques for hardening other Chinese computers against future surveillance by the N.S.A."

So he is offering aid to the Chinese government in the form of top secret US data. I understand the need to have whistle blowers and respect that some things need light shined on them. However, I draw the line at specifically assisting foreign governments who are often hostile to democracy and the West. If the reverse happened and a Chinese security contractor fled to the U.S. with state secrets I would be less worried but I do think that person would be a traitor to China.