They are called "unknown attackers" in the article at TorrentFreak, with the obvious suspicion that the movie and TV copyright holders are behind the whole thing. "Copyright police" is just me being tongue-in-cheek as usual.
If a more solid lead shows up as to who is actually conducting the IPv6 flood attacks, I'll update the story.
In the mean time it does go to illustrate another point. No matter how good software is, sometimes it can simply be outdated by circumstances that are not foreseen by the authors. Older versions of uTorrent have been working very well for many dissatisfied by the changes brought about by BitTorrent Inc. in the newer editions of that software. But that may be coming to an end.