Think of the fediverse as a federation of states, some bigger, some smaller, but all in the same ballpark. Threads had 10M signups just yesterday, which is more than the whole existing fediverse combined. Federating with them would be like the US adding China as a state - it would immediately be the biggest state by far, and would have the power to set politics for all others. And we know what sort of politics they would set, right?
You don’t have the whole context. The relevance of it being interstellar is that, at the speeds it was travelling, it should have vaporized completely when entering out atmosphere. The fact that pieces survived reentry is anomalous, as it indicates that it must have been made from alloys not naturally present in any other object that we’ve seen entering out atmosphere from outer space.
If those alloys are natural (but never seen before) or artificial (and so created by some other intelligence), that’s the question here.