BBPress si permite el posteo "anonimo"
Forum Settings Cita: Anonymous posting
Any site visitor can post a new topic or reply without the need of logging into your site. They will still be required to enter a name and email to post, but will not be required to create a username or password and will not be shown in the list of WordPress Users.
Para ocultar el root del foro también existe una
opción Cita: Forum root should show – Sets your forums to display an index of your forums or a list of the most recent topics.