Having worked in the realm of government contracting, they often hire people who can get things done but don't necessarily have the appropriate depth of knowledge to make the kinds of claims that he is in fact making. He may have plenty of expertise in various areas but that doesn't make him an expert in the types of things he is leaking. Domain knowledge typically lags behind technical knowledge in this field - it's one of the hallmarks of IT that you can work in any specialized domain without knowledge of the specialty itself. It seems to me that your argument is just as baseless as an argument to the effect that he was incompetent, which the OP is not making.

While I'm behind whistleblowers in general, and I agree with the linked article that completely irrelevant information is being used to smear Snowden, I do find a number of things suspicious. We know practically nothing about this guy, and it's not so easy to tease out true facts from what's currently available.

(W.r.t. his interview with the Guardian reporter in Hong Kong,) I'd say his articulateness attests to a level of intelligence that goes WAY beyond the "people who can get things done but don't necessarily have the appropriate depth of knowledge" stereotype.

He comes across as a person who asks questions, a person with genuine curiosity. In fact, I'd say that his lack of high school diploma is actually a positive attribute in light of the fact that he was able to do his job enough to get paid $200k, i.e., the skills to perform his job came out of somewhere, didn't they? Without formal education, it shows that he picked them up himself. (On the other hand, the most robotic, unquestioning, confirming do-anything-for-social-glory types are almost always the "well-educated"; they perceive that they have a lot to lose by asking questions and have excelled at playing the hierarchical authority structure game, i.e., doing what pleases parents, teachers, professors, etc; in return for good grades and appreciation, which ultimately builds up to being the boss' pet in return for a good bonus).

The question isn't the authenticity of that document, it is the interpretation of that document. The only people who have seen the full presentation and are speaking about their interpretation are people who may not have the expertise to interpret it properly. That is where people can start to question Snowden's intellect or education.