The torrent has been removed from the site, so you can no longer download the torrent file, but the torrent itself should still work if you still have it. There are many torrents like that. Don't quote me on this, because this is just my theory, but I think it's so people who are still downloading the torrent can complete it so the bandwidth they have used already is not wasted, while still keeping people from (starting) downloading the torrent.