That's a good suggestion about the allowing the MP's assign utilities to portfolios. I went with the per bill framework because I thought it was simpler, and was trying to find the simplest formalization I could that would capture the interesting parts of the parliamentary model.

But perhaps dependence of bills on each other (or in the real world of actions that one's moral parliament might take on each other) might be a key feature?

It might be interesting to see if we can analyze both models.