That isn't really about the "term of protection" though, but rather the validity of the copyright claim.

'Term of protection' == 'any valid copyright claim it might once had had or been eligible for if properly registered, as opposed to the questionable claims of the current licensors'. I don't want to type all that out every time, and I don't want to make a possibly-inaccurate claim that it was never ever in copyright because I haven't checked all the primary sources for myself.

That's why I referred you to external sources for the lawsuit, because I don't want to make definitive comments about the legal merits of either side's case in this thread - it's been a few months since I even looked through the complaint.

I'm not sure how hard it is to say "[copyright claim] is not valid". It's kind of hard to discuss thing if you come up with your own meaning of things.