Do you have any evidence for those claims, or anything resembling those examples?
Music copyright has long expired for classical music, and big shots are definitely not exempt from where it applies. Just look at how much heat Ed Sheeran, one of the biggest contemporary pop stars, got for "stealing" a phrase that was literally just chanting "Oh-I" a few times (just to be clear, I am familiar with the case and find it infuriating that this petty rent-seeking attempt went to trial at all, even if Sheeran ended up being completely cleared, but to great personal distress as he said afterwards).
And who ever got sued for using dev tools? Is there even a way to find that out?
https://www.radioclash.com/archives/2021/05/02/youtuber-gets...
For being sued for looking at source here is the first result on Google
https://www.wired.com/story/missouri-threatens-sue-reporter-...
Among many others. Classical music may have fallen into public domain, but modern performances of it is copyrightable, and some of the big companies use copyright matching systems, including YouTube's, that often flags new performances as copies of recordings.
But surely the answer should be to fix the broken YT system and to educate politicians to abstain from baseless threats, not to make AI researchers pay for it?
Anyone with a mouth can run it and threaten a lawsuit. If fact, I threaten to sue you for misinformation right now unless you correct your post. Fat lot of good my threat will do because no judge in their right mind would entertain said lawsuit because it's baseless.