If we could fax ourselves to Mars, or undergo uploading, then still wonder whether we're still "us" -- the same as we wonder now when such capabilities are just theoretical/hypotheticals -- that should count as a strong indication that such questions are not very practically relevant, contrary to Aaronson's assertion. Surely we'd need some legal rules, but the basis for those wouldn't be much different than any basis we have now -- we'd still be none the wiser about what identity means, even standing around with our clones.

For example, if we were to wonder about a question of "what effect will a foom-able AI have on our civilization", surely asking after the fact would yield different answers to asking before. With copies / uploads etc., you and your perfect copy could hold a meeting contemplating who stays married with the wife, and still start from the same basis with the same difficulty of finding the "true" answer as if you'd discussed the topic with a pal roleplaying your clone, in the present time.