Nope, atproto protects against this. See https://atproto.com/guides/overview#account-portability
Basically, a user and all their post history are stored in a "repo", similar to git repos, where every post is signed, and each user has a recovery key. Users can switch servers (e.g. pushing their repo to gitlab instead of github) without cooperation from the original server.
There's nothing a Bluesky PBLLC engineer can do to turn this functionality off. It's how the protocol is designed.