How, exactly, Snowden has committed espionage has never been made clear. Did he gave valuable information to a country engaged in war with the U.S.? No one has alleged that he did. Apparently his "crime" was telling the American people the truth about our own government's spying upon us - a truth that our government has systematically lied about over the years in testimony to Congress. In what warped reasoning is telling the truth about that an act of espionage?
But our government needs that charge brought against Snowden, so we can pressure foreign governments to turn him over to us. And if a government sees through that, and decides not to give us Snowden - because he's a whistle blower not a traitor - then that government gets criticized not only by Schumer, with his absurd analogy between Snowden and Syria, but by Jay Carney, John Kerry, and the whole weight of the elected and appointed American government.
And this of course is exactly what the government most wants. Redirect everyone's attention to the flight of a whistle blower labelled traitor, and the countries who might object to that label, rather than the illegal activity that the whistle was blown upon: the US government's illegal collection of communication information from the American people, and its repeated lying about that every chance it got.
See also: David Gregory vs. Glenn Greenwald: Lessons about So-Called Progressives