Just anecdotal evidence, but I do think the author is wrong in suggesting YIMBYs are open to affordable housing.
My neighborhood in Chicago had a controversial affordable housing complex get built. It was a mix of affordable and market-rate units, with a priority for veterans, seniors, and those with disabilities to take the affordable units. This was not section-8 housing, or government housing.
The prospect of its construction ended up fracturing an unofficially YIMBY neighborhood group, splitting it in two: Those who wanted 100% market-rate units and felt the affordable apartments would "end up like the next Cabrini green". It culminated in several individuals, one YIMBY-aligned individual launching unsuccessful lawsuits, and ultimately culminated in the alderman who approved the project losing in a massive landslide to a neighborhood that had reelected him twice.
My neighborhood in Chicago had a controversial affordable housing complex get built. It was a mix of affordable and market-rate units, with a priority for veterans, seniors, and those with disabilities to take the affordable units. This was not section-8 housing, or government housing.
The prospect of its construction ended up fracturing an unofficially YIMBY neighborhood group, splitting it in two: Those who wanted 100% market-rate units and felt the affordable apartments would "end up like the next Cabrini green". It culminated in several individuals, one YIMBY-aligned individual launching unsuccessful lawsuits, and ultimately culminated in the alderman who approved the project losing in a massive landslide to a neighborhood that had reelected him twice.