I would guess people are searching "bittorrent [copyright material]" and someone has had their lawyers shout at google for it, because it could be seen as prompting users into pirating. Like "torrent li[nkin park]" might have got them in trouble because before the person was just searching "torrent li[nux]" so now a user who wants a legit torrent for linux is being told oh hey you can pirate linkin park albums too!

(I don't agree that this is right, but it seems the sensible explanation to me)