I expect that the blog post is sincere. If the NSA or another government agency wanted to manipulate the discourse on this or a similar site, however, they would (not could, would) do so by setting up a large number of active accounts over a long period of time. These would promote articles without triggering voting ring algorithms.
For the last couple of years I have been an active participant in a part of the blogosphere that is inspired by Unqualified Reservations, a contrarian ("(neo)reactionary") blog. I recently discovered that many of the (active and quite long-standing) blogs and commenters in this online community are fraudulent. It is the situation described in Wikipedia's article on COINTELPRO: "pseudo movement groups run by government agents". This includes people with whom I've had email and even a Skype conversation.
Since the realisation, I've managed to have a little awkward and plausibly deniable dialogue with these "bloggers" and "commenters". The message seems to be that they view neo-reactionaries as a group of potentially violent dissidents whose memes, if they were to spread, would lead to serious public disorder. So it's a political broken windows theory, in which the NSA or FBI are guardians of public opinion (although I happen to be English). Apparently they have been watching closely and collecting "data" for over a year.
So, mtgentry, I don't think you are too paranoid at all. (Although I would have done until quite recently.)