When you get a claim, there is an option to appeal it, all the way to a formal counter-notification which will remove your strike and require the claimant to institute court proceedings against you.
I have even used that a few times, years ago when I still got fired up by this. Now, I just appeal it once on fair use grounds and if it doesn’t get dropped I move on with my life.
Has something changed that doesn’t allow this particular channel owner to challenge the claim? (Genuinely interested as a channel owner myself.)