So by extension, the members don't desire syndicated free reviews from AP but would rather sell those reviews? That would mean this article from AP is saying is that there is low demand for editorially integrous book reviews and not book reviews in general.

The major news orgs like NYT, WaPo, etc usually have their own critics and they syndicate their content to smaller papers so they’re usually competing with the AP. The smaller papers don't have their own critics at all but most syndicate from the bigger papers and the ones that specialize more in non-factual content like Tribune Content Agency and Creators Syndicate.

I think this is just AP cutting the red headed step child because they don’t produce much other opinion content, instead focusing on analysis and factual reporting, so everyone goes to another source that has more depth in their book reviews.