I mean, Anna's Archive was pretty clear about the future bad thing.
Spotify didn't "think", it wasn't just "related", nothing was "undetermined" or "nebulous".
Anna's Archive explicitly announced they were going to start distributing Spotify's music files. It's not even a case of hosting links to torrents but not seeding -- no, they were going to be doing the seeding too. You can't get more clear-cut than that.
I'm not taking anybody's side here, as to what copyright law ought to be, but Spotify isn't abusing the legal process here.