After deleting a user's personal data, her posts are anonymised and their contents deleted. Setting the "deleted" flag allows the forum to display an appropriate notice, hinting at the fact that parts of the discussion have been deleted as a consequence of a deletion request. Therefore, personal data (Name, ID) are not visible anymore within the thread.
However, if someone whose data have been deleted also was the starter of a thread, her name is still visible in the list of all threads in a forum, even though the first post is not visible.
The name of a user whose personal data have been deleted should not be visible anymore, anywhere. At least not in public-facing pages.