Why would a company keep the hard-copy around at the risk of it being inadvertently given away, resold, etc.? It's a huge outstanding liability given that the illegal copying of works -- the other part of that case -- is what they settled out of court for some huge amount of money. Destruction is the only thing that makes sense.

I'm old enough to have been around when DCMA legislation was under discussion. Many people were dead-set against it and raised concerns over matters exactly like this. In Rainbows End (2006), Vernor Vinge wrote about a similar scenario where a robot went through the university library shredding books, and scanned the shredded pieces to recombined them into a digital archive.

Anthropic may be doing shady things and may have even done this on their own recognizance, we just don't know. As it stand, this is 100% a consequence of US copyright law, much of which was written by large corporations to protect their own assets.