[Admin]

In index.php, replace this:

        if ( !isset($forum['moderators']) ) {
          $forum['moderators'] = ' ';
        }

with this:

        if ( !isset($forum['moderators']) ) {
          eval("\$forum['moderators'] = \"".gettemplate('forumhome_nomoderator')."\";");
        }

Now create a template named 'forumhome_nomoderator' and put whatever you want in there.

By the way, this also works in forumdisplay.php for sub-forums.