This is absolutely a bad outcome and I hope the pact prevents this from playing out.
However, I feel kind of ok with losing the subset of users that would accept and use a Facebook implementation of the fediverse. It directly defeats the purpose, regardless of how much better the UI/UX may be, and shows they didn’t understand it in the first place.
I’m struggling to understand it too, especially from instance owners. FB is diametrically opposed to FOSS and decentralized ideals. My only guess is the hopefulness people feel for decentralized internet extends to naivete about FB doing the right thing this time.