Well, Meta has a history of bad behavior in terms of how they treat users on their own systems, but no history at all for how they treat federated systems. You could even go the other way a bit and say that Meta has contributed meaningfully to the open source community with projects like React. (Obviously this is short on parallels as it doesn’t involve their main income streams.)

I would absolutely say that users should not join Threads directly. Meta is already hoovering everything they possibly can about their users. But the mechanism for that hoovering is the app, not the protocol. Any data they get about users that are not on Threads directly is data they were going to get anyway because that’s the design of the protocol; anyone can get that data.

It seems that members of a federated system can’t decide how to treat an entity until that entity interacts with other members. You assess the nature of those interactions, and if they turn out to be bad, you defederate.

What the Mastodon community is doing now looks a bit like “this person drives over the speed limit all the time, so they’re obviously going to steal food if we let them volunteer at the homeless shelter!” But we have no evidence for such unwanted behavior whatsoever.

edit: I saw on another thread that apparently Meta reached out to some Mastodon instances to try to get them to sign NDAs. If true, that’s inexcusable and signals intent pretty clearly. Public protocols must be developed publicly.