support_nag: Query selecting more records than expected

I expect following query in file support_nag.module (about line 62) to select all tickets matching some filter criteria:

      // TODO: Ugly query!
      $sql = 'SELECT n.nid FROM {node} n 
                  LEFT JOIN {support_ticket} t ON n.nid = t.nid 
                  WHERE '. implode(' AND ', $where) .
                 ' ORDER BY state ASC, priority DESC, client';
      $result2 = db_query($sql);

But the "LEFT JOIN" will result in returning ALL nodes - what is probably not intended.