I think people around here have a vastly overestimated opinion of how important the fediverse is to other social media sites.
Within the first 7 hours of Threads, they had 10 million users.
Meta absolutely DGAF about us. They don't have to. Using ActivityPub is at worst an anti-monopoly play. But by the time they turn on federation, all of the people who were going to leave the fediverse for Threads will likely already have done so.