Except we know they're going to digitize it, use that data to feed an AI, and never release it to the world.

Legally they can't, they would immediately land in copyright claim hell.

Most people do not support the destruction of books - it seems like the issue in both cases is copyright forcing the destruction and non-release of the scan.

They don't have to destroy the books to scan them. There are techniques for doing it non-destructively, but they're slower and more expensive. It's cheaper to cut the spines off and drop the stack of papers on a flatbed scanner with a paper feeder.