Lead to severe discounting of the 'reasoning method' that arrived at 3^^^3 dust-specks>torture conclusion without ever coming across the exhaustion of states issue.

This is mistaken. E.g. see this post which discusses living in a Big World, as in eternal inflation theories where the universe extends infinitely and has random variation so that somewhere in the universe every possible galaxy or supercluster will be realized, and all the human brain states will be explored.

Or see Bostrom's paper on this issue, which is very widely read around here. Many people think that our actions can still matter in such a world, e.g. that it's better to try to give people chocolate than to torture them here on Earth, even if in ludicrously distant region there are brains that have experienced all the variations of chocolate and torture.