On what basis do you claim that? Does the following paint the picture of a leftist in your mind?
> And he became furious about Obama’s domestic policies on a variety of fronts. For example, he was offended by the possibility that the new president would revive a ban on assault weapons. “See, that’s why I’m goddamned glad for the second amendment,” Snowden wrote, in another chat. “Me and all my lunatic, gun-toting NRA compatriots would be on the steps of Congress before the C-Span feed finished.”
> At the time the stimulus bill was being debated, Snowden also condemned Obama’s economic policies as part of a deliberate scheme “to devalue the currency absolutely as fast as theoretically possible.” (He favored Ron Paul’s call for the United States to return to the gold standard.) [...] He sent Ron Paul two contributions of $250 during the 2012 presidential primaries.
Ayn Rand seems to have inspired his personal philosophy. [0]
[0] https://fee.org/articles/snowden-s-muse-was-ayn-rand-s-john-...
Glenn Greenwald and Julian Assange both certainly used to be leftists, and may still be at heart, but they've both let personal grudges define their alliances for them and offend a lot of allies on the left. They're certainly not meaningfully right-wing, though.