But normal human beings are extremely good at compartmentalization. In other words they are extremely good at knowing when knowing the truth is going to be useful for their goals, and when it is not. This means that they are better than Less Wrongers at attaining their goals, because the truth does not get in the way.

If you really believe this, I'd love to see a post on a computational theory of compartmentalization, so you can explain for us all how the brain performs this magical trick.