In what sense is this a 'rationalist' position?
In the sense of moral rationalism. The fact that rationalist can be used to refer to rationality or rationalism is unfortunate, but IIRC (to busy to search for it) we've had a few debates about terminology and decided that we currently are using the least bad options.
Stuart has worked on further developing the orthogonality thesis, which gave rise to a paper, a non-final version of which you can see here: http://lesswrong.com/lw/cej/general_purpose_intelligence_arguing_the/
This post won't make sense if you haven't been through that.
Today we spent some time going over it and he accepted my suggestion of a minor amendment. Which best fits here.
Besides all the other awkward things that a moral convergentist would have to argue for, namely: