@fediversereport their opt-in requirement is so obviously bogus – if it were something that Meta's lawyers would insist on, then SMTP should also be subject to opt-in policies (sadly, in practice it almost is these days).
It will be a devastating outcome if online decentralization becomes subject to onerous federal / european-level regulatory baseline requirements in order to enter the market. I hope that the regulators see past this attempt at regulatory capture.
cc @pluralistic