Ok, in my eventual formulation, I’m not actually relying on moral parliaments. However, I will note that in your and Paul’s original formulation of the double-updating paradox, you were writing about bets where your utility is linear in money (e.g. small amounts of money donated to charity).
Here you write “if you ever get evidence that a decision is high-stakes enough and universal enough throughout the universe, EDT may well recommend that you make an exception for it and do a proper double-update on it, which seems bad”. At the point where you are making very high-stakes and universally applicable decisions, I’m no longer convinced you get linearity, and I might bite the bullet that there might be some bets you don’t want to engage in on either side, or the paradox fails in other ways.
Altogether, I still think that my previous answer basically dissolves this paradox.
I think in both cases the decision-correlational reference class you should take into account is not just you learning T1 is true and you learning T2 is true within this particular experiment. It’s every instance across the multiverse where beings similar to you need to make bets about questions they have no clue about. Taking all these correlations into account, the correct thing to do is to bet with 50-50.
I think 2.6 billion people in the US would probably do fine. There is just a lot of land to be farmed in the US. It’s not even clear to me if per capita wealth would be lower or higher if the US had 2.6 billion people—my guess is higher. So I think the miracle leading to a wealthier society today really was economic and technological, and not contraception.