How is this even a bug? Perhaps I am missing something here but isn't this scenario already perfectly handled by permissions?
Admin wishes to "tease" by showing a forum exists but does not wish for everyone to be able to read the forum. I saw requests for how to set this up quite regularly in Support. A dangle the carrot type of approach to get people to post for advanced access or premium content.
Solution: Can see forum = Yes/Can read forum=No
Admin wishes to completely hide private forums from all but permitted groups.
Solution: Can see forum=No/Can read forum=No
Scenario 3: (apparently the case used in this ticket)
Admin wishes to arbitrarily hide/display # topics/posts or last post information based on forum and/or group permissions.
Solution: MOD/style edits