I downvoted those comments because they sucked. They were wrong in systematic ways indicative of a killed mind.
People who err on the side of shutting down discussion and debate are commonly known as authoritarian in nature. I don't think that's a good thing. I would expect lesswrong to err more on the side of preservation of information, and free speech absolutism, designed for ease of reading and information preservation.
Just look at that snippet. The first sentence is awkwardly worded such that I can't tell whether he's committing the bandwagon fallacy, the fallacy of appeal to nature and arguing by definition, or the bandwagon fallacy and the fundamental attribution error. The second sentence is a crude rhetorical appeal. The third sentence wraps the usual total failure to understand that policy debates should not appear one-sided within cringe-worthy phrases pretending the position advocated is nuanced and pragmatic.
I don't have a policy of downvoting political pieces. I have policy of downvoting crap, and downvoting political comments is just what tends to happen.
Summary: I propose we somewhat relax our stance on political speech on Less Wrong.
Related: The mind-killer, Mind-killer
A recent series of posts by a well-meaning troll (example) has caused me to re-examine our "no-politics" norm. I believe there has been some unintentional creep from the original intent of Politics is the Mind-Killer. In that article, Eliezer is arguing that discussions here (actually on Overcoming Bias) should not use examples from politics in discussions that are not about politics, since they distract from the lesson. Note the final paragraph:
So, the original intent was not to ban political speech altogether, but to encourage us to come up with less-charged examples where possible. If the subject you're really talking about is politics, and it relates directly to rationality, then you should be able to post about it without getting downvotes strictly because "politics is the mind-killer".
It could be that this drift is less of a community norm than I perceive, and there are just a few folks (myself included) that have taken the original message too far. If so, consider this a message just to those folks such as myself.
Of course, politics would still be off-topic in the comment threads of most posts. There should probably be a special open thread (or another forum) to which drive-by political activists can be directed, instead of simply saying "We don't talk about politics here".
David_Gerard makes a similar point here (though FWIW, I came up with this title independently).