I think the entire forum should be divided into three areas. One that is visible to search engines, and prior to signing up. A second that is available after signing up, and lastly the final area after the user has been vetted. What that vetting process is: days after signing up or after X number of believable posts or TBD (To Be Determined).
Since these divisions would be totally unknown to the potential user, there would be no misunderstandings. In fact it would probably prevent misunderstandings as potential trolls would not see discussions about them (right or wrong), since those discussions should happen in the third area.