First, every single one of Molesworth’s posts are now available to Meta, including all the replies they make to everyone including people who don’t follow anyone on Meta’s server. In other words, Meta gets access to posts from people who may very well have an issue with that.

But this is already the case. If Meta wants fediverse content, it's so much easier to just scrape it than it is to build a fully interoperable ActivityPub service. They can get all data with a crawler instead of waiting for individual users to follow each other.