Eliezer explicitly forbade discussion of FAI/Singularity topics on lesswrong.com for the first few months because he didn't want discussion of such topics to be the primary focus of the community.

Again, "refining the art of human rationality" is the central idea that everything here revolves around. That doesn't mean that FAI and related topics aren't important, but lesswrong.com would continue to thrive (albeit less so) if all discussion of singularity ceased.