The fediverse is like 2 to 3 million, Threads is about to hit 100 million. Instagram has billions. Something telling me that redesigning their entire infrastructure just to attempt to absorb that little amount of people who are known to be hostile towards them, is not their actual goal. Yet the fedi seems to think this makes sense somehow.
It makes way more sense to me that the experiment with federation will ultimately be to connect their own services. For example, so you can follow an instagram thot from your facebook, or you can message someone on whatsapp using facebook messenger.