The author is in dire need of a literary review.

Slow Down has an extraordinarily myopic view of theory that doesn't appear to have incorporated anything (maybe a little Graeber) that has been written outside of Marx in the last 150 years. The author attempts to reproduce anarchism from first principles relying on some unpublished musing by Marx near the end of his life rather than just reading the writers who've already addressed these ideas, at length, and much better. But that would require them to stick their head outside of the sphere of academic Marxism.

If you dumped all of Chapter 4 (Marx and the Anthropocene) and struck everything that mentions Marx from the text... you might have a descent essay outlining some of the broader ideas in the area Degrowth. But still nothing that a reading of Wikipedia wouldn't have gotten you.

I guess if you have any ML friends who insist on some kind of Marxist orthodoxy for their praxis -- you can give them this book.