I think we should let them consume Fediverse content but not create it.

If Meta proposes to let Instagram users follow people on Mastodon or whatever, that seems like a reasonable compromise - they get to keep people on their feeds viewing ads and we get more reach - but they shouldn't have the power to leave and take a large % of Fediverse content with them; if you want to make a post, you need to do so from a non-Meta-controlled instance in a non-Meta-controlled app.