Overall, in this case you cannot assume to be right by relying on fair use, because fair use as a legal concept implies that there has to be a court decision in order to exist.

And all of the required measurements in order to apply fair use are almost impossible to prove, therefore it is an unlikely case to win in court.

I agree with the political sentiment in this discussion, and I have a biased opinion, too - but when talking about pushing the needle in a specific direction the maintainers of youtubedl did a bad job at doing so.

I mean, they have one of the most powerful industries siding against them, with nearly unlimited funding, so it is obvious that this was bound to happen and they should have been more careful.

Especially when they, as a project, cannot afford lawyers to fight potential battles in court.

That's why I described it as an unnecessary attack surface, because that's what it is.

Don't give them reasons to push the needle.