If #Meta wanted to mine your content to populate #Threads but didn’t want to federate their own content to the #Fediverse, they wouldn’t use ActivityPub for this purpose. They would use RSS—which is enabled by default on most Mastodon servers. In many ways, it would probably be easier for Meta to do this too.
My expectation is that meta would allow users to see federated content but would not allow threads to be federated.
This would provide incentive for people to move to threads. After a while, the walls around the garden would grow.
It's the same embrace, extend, extinguish model they used with MySpace when they rolled out Facebook connect.
MiKlo:~/citizen4.eu$💙💛
•RSS is a 'view-only' protocol. And by using activitypub meta can control precisely which elements (post publishing, commenting, boosting, liking) will be available and which way.