Your question is very good. I was also worried about it. This plugin is doing same things with "Delete" in user profile page by admin. To be precise, this plugin is using qa_delete_user(app/users-edit.php) core function in application layer. Not qa_db_user_delete (in db/users.php).
Delete $userid and all their votes and flags. Their posts will become anonymous.
Handles recalculations of votes and flags for posts this user has affected.
Vote and flags are deleted, but posts will not be deleted. These will remain as anonymous posts. In the future, if specification of this function is changed, the process of this plugin also will change automatically.
In addition, I did not add button for hiding own posts in user profile page. It is because, this button is mainly used for spam. And, when a part of the conversation will be deleted, conversation becomes strange.