bbPress.org

There will be an update released in the not to distant future addressing these 2.1 bugs.

The visibility of forums is/should be at the moment:

Public – Anyone can see these forums

Private: Only logged in registered users can see these forums

Hidden: Only Moderators/Admins can see these forums

As for a work around, I would suggest a static page or text widget with links to the forums you want publicly listed