The author seems to focus a lot on the idea Marx was a degrowther, which yeah probably isn't true but just starts to sound more like ecclesiastical arguments on what Jesus really meant as opposed to talking about the actual issue at hand.
There rebuttal mostly seems to be a techno-optimist view that a lot of pro-growth Marxists have but doesn't address the consumerist lifestyle of people in the west. The current growth of the economy powered by western consumers driving their cars to Walmart to buy cheap plastic stuff made by exploited workers from the global south that will end up in a landfill in a year probably shouldn't be a thing both ecologically and socially.
The truth is if there was true global socialism a lot of the consumerist western lifestyle will probably go away as workers from the global south will refuse to produce that stuff or produce it at such a cost to westerners that they won't want it. Denying this will only lead to tension post revolution.
We should instead focus on the positives of de-growth, that is less work. Yeah, you may not be able to buy that new pair of shoes every other month, but you'll only work 10 hours a week.