Just a minor thought connected with the orthogonality thesis: if you claim that any superintelligence will inevitably converge to some true code of morality, then you are also claiming that no measures can be taken by its creators to prevent this convergence. In other words, the superintelligence will be uncontrollable.
As far as I can tell, it's pretty common for moral realists. More or less, the argument goes:
So, the moral realists believe a superintelligence will converge on true morality. Do they also believe that superintelligence is controllable? I had thought they would believe that superintelligence is uncontrollable, but approve of whatever it uncontrollably does.