There has been some good commentary about this on Mastodon, but the long and short of it seems to be that federation is actually a pretty terrible way to harvest data.

The entire fediverse is based heavily on openly accessible APIs - Meta doesn’t need to federate with your instance to scrape your data, there’s really not much that can be done about it.

The real solution to Meta’s unethical behaviour is unfortunately going to be legislation, not technical.