Apparently deleting one's thread account will also delete ones Instagram account.

I don't think it is an overreaction. There is a reason Meta won't allow Threads accounts to be deleted without also deleting your Instagram account. They are holding people hostage in a sense. It is a deliberate move, and there is no reason they couldn't disassociate a Threads account from an Instagram account and delete it. Hell, no need to even disassociate it at all.

Isn't a major reassurance from Eugen, and others who also signed Meta's NDA, that you can move your account from Threads? How is that truly possible if they don't let you delete the account without also deleting your Instagram account?

This is the type of malignant and anti-open behavior we can expect from Meta. And they are doing it right out of the gate, before they even embrace ActivityPub as they rush to capitalize on Twitter's mess.

I stand by my previous statements: Meta's vision of Threads is to suck up as much growth in our community, then wall it off with tactics like the above, all while embracing open standards.

It isn't like we don't see it happen elsewhere. Google did it with their "proprietarization" of RCS. Google promoted its growth and adoption, then slammed the door shut. That is why Signal and others do not have RCS; Google refuses to allow competitors to have access to it. They've walled it off. Only preferred partners, like Samsung, are allowed to dabble in it now. And so, too, will Meta go that route with ActivityPub if we let them.