Not to put words into Justin's mouth, but I think he saw the correlation as one defining what "personhood" was. If it could be established that an animal outside of the human race was worthy of being entitled to all of the privileges of a "person", then that paves the way for an AI to be afforded the same rights.
I agree, but notice that the AI&Singularity subforum is in the Computing forum... I see a difference between ethical valuations and, say, the theoretical aspects of cybernetics and technological progress. Yet if the modeling of trends in "normative evolution" could be refined to the point of producing useful predictions (which I am highly skeptical of), then incorporating said modeling into the broader modeling of tech trends would be appropriate. That was my basic point, and since I have (and have always had) a hard time seeing how such a synthesized enterprise could be methodologically grounded, the correlation is not clear from my perspective. But this is just me being nitpicky.