(Last I checked, Robin Hanson put probability of hard takeoff at less than 1%. Unfriendly singularity is so bad an outcome that research and discussion about hard takeoff is warranted, of course, but is it not a bit of an overreaction to suggest that this series of articles might be too dangerous to be made available to the public?)

If the probability of hard takeoff was 0.1%, it's still too high a probability for me to want there to be public discussion of how one might build an AI.

http://www.nickbostrom.com/astronomical/waste.html

Because the lifespan of galaxies is measured in billions of years, whereas the time-scale of any delays that we could realistically affect would rather be measured in years or decades, the consideration of risk trumps the consideration of opportunity cost. For example, a single percentage point of reduction of existential risks would be worth (from a utilitarian expected utility point-of-view) a delay of over 10 million years.