I think you're on to something here. I have a feeling that the author has already come to the self-serving conclusion that open source software is somehow harmf

I think you're on to something here. I have a feeling that the author has already come to the self-serving conclusion that open source software is somehow harmful to developers, and is trying to reverse-engineer a justification for that statement -- ideally one with moral implications like "it takes money away from developers in low-income countries".