Whenever I make a choice, there are branches that made another choice. But not all branches are equal. The closer my decision algorithm is to deterministic (on a macroscopic scale), the more asymmetric the distribution of measure among decision outcomes. (And the cases where my decision isn't close to deterministic are precisely the ones where I could just as easily have chosen the other way -- where I don't have any reason to pick one choice.)

Thus the thought experiment doesn't show that I don't care about all my branches, current and future, simply proportional to their measure.