The number of observers in a universe is solely a function of the physics of that universe, so the claim that a theory that implies 2Y observers is a third as likely as a theory that implies Y observers (even before the anthropic update) is just a claim that the two theories don’t have an equal posterior probability of being true.
The number of observers in a universe is solely a function of the physics of that universe, so the claim that a theory that implies 2Y observers is a third as likely as a theory that implies Y observers (even before the anthropic update) is just a claim that the two theories don’t have an equal posterior probability of being true.