I am in no way techy, but from what I gather because the posts are federated they are also stored on the other instances as well, so posts are still visible. In the post announcing the shuttering of .ee they specifically mentioned adding a note on your profile to link to your new profile, so people can find your new profile after that shut down. That implies to me that everything not intentionally scrubbed remains open/visible long after the shut down of the original source.

Again, though, not techy, so I may be vocalizing from my posterior