Judging by the kneejerk pattern of the voting on the comment thread, it's largely zealots.
I suspect it's mostly because people are so fed up with everything connected to the current Washington establishment that they'll vote for anyone who sets himself up as an outsider. Ron Paul's been one of the few candidates that's consistently against the Iraq war; many people will vote for him on that basis alone, regardless of the rest of his positions.
I think it's telling that the friend who's been trying hardest to convince me to vote for RP is a pro-choice Green Party atheist. When I showed him Ron Paul's recent voting record (which included a bill to eliminate all federal laws on abortion, a bill to privatize a large federal wildlife refuge, and a bill to prevent laws on school prayer), he said "It doesn't matter. He's against the Iraq war, and that outweighs everything else." He's willing to set aside every other political belief he has for that one issue. I suspect a decent-sized portion of the American electorate is the same.
It could also be argued that your comment was completely off topic for the link, kind of like the guy who always complains about the xkcd links on reddit. Would you argue that xkcd is driven by zealotry, or are there just a lot of reddit users who who actually like seeing xkcd? (and again, I'm one of the people who occasionally upvotes the xkcd comics)
For a long time the quality and diversity of links in Reddit was quite stable, reflecting the strong core userbase. Major systemic issues [1] led to more junk-food like submissions edging in, and slowly the forces involved drove out the original core audience, long-september style. This process continued gaining momentum, until fairly quickly lurching to the new stable state we find it in today. A similar process can be observed in wikipedia: those who care the most, have the most time, and the most tolerance for internet drama naturally dominate: the young and the passionate.
1. a) Reddit conflated two distinct actions into a single vote: training the recommendation engine (vote on what you like/dislike) and judging quality (what is good/bad). This lead to a culture of voting on taste, tending the system away from voting on quality, partly because of: b) The nature of these systems, like the mainstream media, is to tend to the lowest common denominator as audience size increases. This should not have been surprising.
How to avoid these issues? Paul's suggestion (somewhere else on this page) about automated topic clustering is a good one. A similar approach I favor is encouraging clusters of users to form naturally, using a collaborative classification/filtering approach; even something as simple as allowing three tags per link could do this. Once clusters are established, it should be much easier to allow users to opt-in or out of the clusters they like/dislike. The editor/oracle approach and/or weighted voting should also work, but seems like a lot more effort.
[ahem. I feel like I should mention I'm somewhat biased, as I'm now working on something experimental in this domain]
pg> What if the upvoting really is representative of a large number of the users?
What if most of the users on reddit are, at this point, zealots, due to the effects of crowding out more moderate users?