You may not understand how a torrent works.
In order to "upload the files" there is no passively seeing who downloads them.
Downloading a .torrent file itself isn't illegal.
The torrent file links you to someone who has the files in question, and that person actively uploads them to you.
So what has happened is the copyright holder posted a link to their files on one of their computers, and actively uploaded the files to several users, who in turn uploaded them to more users.
Prenda directly uploaded their copyrighted material to users who requested it. This is not a passive function.
This would be the same if you walked into a store, and the owner pulled a book off the shelf, walked out side and handed it to a stranger.
Said nothing, and walked back inside. Then phoned the police and said you didn't have permission to have that book from their store.
Prenda, should they have done this, circumvented all password and user functions to protect their content, and uploaded it freely to those who requested it.
It would be like if you fell on a webpage looking for content, and it started playing in the video box, then they sued you for not signing in / paying for their content.