Can you really see him as a political candidate? personally I think he the government will pardon him sometime in the near future and he will end up working for one of the unicorns (fb/google etc).
Pardoning him would set a precedent indicating leaking top-secret documents when you think you have a higher moral purpose is an 'acceptable' thing to do. I'm wholly on Snowdens side in these particular circumstances, but even his case is, sadly, subjective. I believe knowing you could lose your freedom is a healthy filter to ensure people act as responsibly as possible.