I think the topic is “evidence of infringement is no longer readily available” not “suddenly, there is no infringement!”
The evidence of infringement would be apparent when b and c were colocated and there was a utility next to them for XORing files and piping it into VLC
I didn't read it that way - the OP said "liability", after all, not "detection".
But, meh, could just be he meant "won't get caught" and not "liability"; I make mistakes in comms all the time, after all.