In the US, copyright is implicit. All work is instantly protected by copyright the moment it is created. Registering with copyright office is optional/voluntary. I think the judge’s comments that you are referring to was probably referring to the works where copyright protections were waived by the artists for works placed into public domain (which, on Deviant Art, covers a vast amount).
Yeah, this was predicted by everyone, long in advance. The surprising thing here is how long they’ve managed to cling to life. I expected them to be deceased by now. I didn’t think they’d last another three years, let alone five.