There are many print on demand services on the internet (lulu.com being a particularly good example), so the cost to the author is zilch, to cancel it on the basis of a torrent is to cut off what would otherwise be a perfectly good business model.
All this chap has done, is guarantee that the torrent will be used. If he'd kept quiet, chances are most of the Amiga community would never have even known of it's existence.
Well played.