I think most people who support Snowden don't think he's guilty as you do. You insist he commited a crime, and you claim that it is a fact. The facts, though, are that he revealed classified documents to the public, and not that he commited treason under the Espionage Act of 1917. Amongst the people who revealed classified documents and then were tried under the act, most (like Manning) were found guilty, but Ellsberg was not. Further, the supreme court has never discussed the constitutionality of prosecuting whistleblowers under this act. Legal precedent is mixed and Snowden's guilt is far from settled. I'm quoting the friggin summary here:
More importantly, the current state of whistleblowing prosecutions under the Espionage Act makes a truly fair trial wholly unavailable to an American who has exposed classified wrongdoing. Legal scholars have strongly argued that the US supreme court – which has never yet addressed the constitutionality of applying the Espionage Act to leaks to the American public – should find the use of it overbroad and unconstitutional in the absence of a public interest defense. The Espionage Act, as applied to whistleblowers, violates the First Amendment, is what they're saying.