They don’t gain much adding fediverse users to the content mill. I have a hard time believing anyone at meta wants to give us access to “their” content without the reciprocal user data and ad attention in return. Hell, Reddit just imploded to rid itself of “freeloaders”.

They saw an opportunity to take twitter’s users, they probably used activitypub because it was fast. If they start federating, we can decide how to handle it. They will win the war for users, but we can have a nice space that they aren’t allowed to touch if we want it.