A set of differential equations that describe its behavior as a dynamic system where the properties of various parts depend on each other, would still be an algorithm.

Sure, but that's not the sense of "algorithm" that was being used here.

If an output can't be modelled with a utility function, it is non-computable. If humans can't be modelled with utility functions, that is a proof that a computer program can't be intelligent. I'm not concerned with whether this is a good model. I just want to able to say, theoretically, that the question of what a human should do in response to a situation, is something that can be said to have right answers and wrong answers, given that human's values/preferences/morals.

None of this is being questioned. You said that you're not concerned with whether this is a good model, and that's fine, but whether or not it is a good model was the whole point of my comment. Neither I nor van Gelder claimed that utility functions couldn't be used as models in principle.

All this harping about whether utility functions can model humans is not very relevant to my post. I bring up utility functions only to communicate, to a LW audience, that you are only doing what you want to do when you behave morally.

My comments did not question the conclusions of your post (which I agreed with and upvoted). I was only the addressing the particular paragraph which I quoted in my initial comment. (I should probably have mentioned that IAWYC in that one. I'll edit that in now.)