There is no evidence that the availibilty of Tor decreases sales in the works themselves. Quite the contrary, while i don't use z library specifically, i often use the open librarys to speed read through certain sections before i decide to buy the print, or through kindle just because the experience is that much better.
The powers that be offer us a contract where all our data is open and available for selling, training, marketing and general manipulation but yet when someone maintains a decentralized directory of books they get punished by the full extent of the law.
In this particular case, the United States can't even provide a list of copyrights that are being violated and the judge was removed for collusion. This is where my taxpayer dollars are going?...