You're kidding me right?!? You honestly think the era he lived in was fair and just to people like him? Do you know how many lynchings there were in Florida alone? Does the name Emmett Till ring a bell? What did you think MLK fought for?
Do any of you believe that there would have been a new Letter from Birmingham Jail if Snowden were imprisoned? Keep in mind the US authorities are calling this civil rights whistleblowing "treason". Aiding the terrorists and enemy combatant status cannot be far behind.
Like it or not, the rule of law has been badly damaged by the endless emergency.
These days you do your nonviolent resistance from behind the safety of a diplomatic minefield.
Not by anyone who understands the legal definition of treason. Among other things, treason presupposes formally declared hostilities. Even Cold War turncoats convicted of espionage for aiding the Soviet Union couldn't be charged with treason, since technically, we were never at war with the USSR.
But of course, they would just as well argue we're in the War on Terror. It would be an obvious flimsy justification but, there you are.
A far more likely tack would be trying him under the Espionage Act, which is vague enough to make prosecution easy and defense hard. Relatively speaking, at least.
That hasn't stopped us from starting or entering numerous wars, of course... they're just "undeclared." Cuts down on the paperwork, dontchaknow.