It's not true that NSA-has-root was simply Greenwald's interpretation. Barton Gellman and Laura Poitras took the same interpretation in the Washington Post's first story http://articles.washingtonpost.com/2013-06-06/news/39784046_... (the paragraph suggesting that this might be a misinterpretation was added later). Greenwald did also have a coauthor on the Guardian story too. What does seem to be true is that Greenwald backed down from the claim more slowly than WaPo or even the Guardian. Still the decision to focus on Greenwald here does seem like someone's rhetorical ploy, if it isn't simply glee at the chance to get at a much-disliked figure.