Snowden is a man who will have had a security clearance to handle highly sensitive information and will have signed agreements with the CIA and his employer not to disclose that information, in return he was highly paid. Snowden chose to breach both agreements and go public, he knows what he is doing, his offences are criminal. The nature of the information he is disclosing is irrelevant. Can't do the time? Don't do the crime.
What if what he was doing was unconstitutional?
What does he do then? Who is the higher authority? The NSA or the Constitution of the USA?
NSA tried to shut this guy down too but are unable to.