Oh, I get that theory, though I'm not sure I completely agree. Either way, unless I completely misunderstand how ActivityPub works, their instance can effectively be isolated to its own little sandbox depending on how many other instances decide to share with them. Further, if you're on an instance that decides to share w/ Meta's, you can skip over to another one that doesn't. So Meta can be isolated by instance owners and/or users.

Let them! There's nothing saying other instances have to federate with them. Kind of the beauty of the whole thing, really.