Looking at copyright claims I have on my channel (these are valid music claims, for what it's worth), I see a dispute option labeled "The video is my original content and I own all of the rights to it", which I think covers the case you're describing.
That's not quite the same thing. For example, a work may be public domain, in which case it is not your original content, but nobody else owns the rights to it either.
There's a different option for if the video is public domain or otherwise not copyrightable to handle this case. I assume that that "lawyerly language" is to dissuade users from abusing the process and choosing an option when it's not really true.
Nearly every video is going to be an amalgamation of original content, licensed work, and public domain work, yet the listed alternatives you've presented both clearly apply to entire videos, forcing the content creator to lie if they want to go forward with a dispute.
It seems quite bonkers that you disagree with the "disputes are discouraged by forced lying" narrative yet keep posting evidence to support it.
Ah well. It's not my fight. I should be grateful for that.
