Not sure if you are trolling, but no

Meta is joining the Fediverse not because it needs the people currently on the Fediverse, but because it needs a regulatory figleaf to protect itself from monopoly charges. At Meta's scale, there are 0 users on the Fediverse right now. There is no market benefit to getting Fediverse people to move to Meta

What Meta gets out Threads/Fediverse compat is that suddenly Instagram is not technically a walled garden with platform lock-in, so while the number of people who'll migrate from Instagram Threads to the Fediverse is going to be tiny they suddenly look a lot less like a mean monopoly to regulators

At some point they might remove the Fediverse compat. The people currently screaming about embrace-extend-and-extinguish because Meta is joining will then scream about bait-and-switch even though they've had Threads defederated the whole time. The Fediverse will still be there. That's the cycle of life