First, I think that your an-cap associate misunderstands what was meant (at least by Bookchin) by Post-Scarcity Anarchism.
Second, I felt like there was something missing from your alternate take on PSA that Bookchin talked about in said essay. I went back and took the book of the same name off the shelf. You should know that I revile revisiting Bookchin.
Third, I got three pages in and thankfully was able to remember what seemed lacking:
Post-Scarcity Anarchism (yes, I keep capitalizing it, because I am sure someone has a different definition than that which is a cornerstone of Bookchin's work, which is what I am addressing) is a libertarian strain of thought that believes that the advent of "cybernetics" (aka information technology & automation, which is how Murray defines "post-industrialism") creates an as yet unknown opportunity for the development of a truly human freedom (as opposed to the freedom experienced by, say, a mere animal).
This is not mere autonomy; it is the chance to learn, to appreciate and explore art, engage in lively debate upon the topics of the day, and do all that shit that apparently (according to the Dean) makes us uber-animal, as opposed to, say, a beaver. The foundations of Post-Scarcity Anarchism are solidly rooted in the Marxist materialism the dean carried over from his youth as a Stalinist, and his young adulthood as a Trotskyite. He held on to these ideas through his time as an anarchist, and it is no surprise he ended up renouncing such for a sort of eco-radical social-democratic perspective.
Missing from this perspective are critiques of technology as an ideology, humanism, historic materialism (so far as I understand it), civilization, democracy, and many more things. If I could grossly boil down Bookchin's thesis in PSA would be: Better living through wired, eco-conscious, vibrantly democratic living.
If you think life will be better lived with all those qualifiers, I think AK Press has a special deal on all the reprints of his books they did to capitalize on his death.