In talking to people at the NSA I get the impression that supporting the EFF is not considered a warning sign that you might leak information, and indeed, many either outright support the EFF or at least share its goals.
Part of this hubris, the firm belief that since "we do no wrong" that therefore something must've been wrong with Snowden -- something above disagreements about mere politics.
Part of this is the experience of the intelligence community in developing humint assets in foreign countries. Sincerely held beliefs is not why people turn. Instead, it's money, sex, embarrassment, personal crisises, emotional problems, and so on.
So when looking at Snowden, or Chelsea Manning, or Reality Winner, they are convinced it cannot have been sincerely held beliefs, and analyze these people in hindsight with the same techniques for recruiting foreign spies.
I'd probably agree with their view most of the time for most of these leakers (also, Thomas Drake). But in the case of Snowden, I do believe that "sincerely held beliefs" played more of a factor in his decision to leak. Maybe it's because I share those beliefs.
