If your forum has a lot of smart people, and they read the recommended readings, then the more people who participate in the forum, the smarter the forum will be.
If the forum can be said to have an intelligence which is equal to the sum of its parts, or even just some additive function of its parts, then yes. But this is not reliably the case; agents within a group can produce antagonistic effects on each others' output, leading to the group collectively being "dumber" than its individual members.
If those people aren't discouraged from posting, but are discouraged from posting stupid things, your forum will trend toward intelligence (law of large numbers, emergence with many brains) and away from being an echo chamber (law of small numbers, emergence with few brains).
This is true in much the same sense that it's true that you can effectively govern a country by encouraging the populace to contribute to social institutions and discouraging antisocial behavior. It might be true in a theoretical sense, but it's too vague to be meaningful as a prescription let alone useful, and a system which implements those goals perfectly may not even be possible.
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).