He talks about code, and Copilot works with code, so I'm not sure how it "applies to any".

If you mean that if you make a "random mashup of existing, copyrighted, hegerogenously licensed" works of art (audio/video), it also applies that you might be sued for it, then yes.

But that's not much of an issue with Copilot if you're using it for enteprise code that's already a mashup of copypaste "existing, copyrighted, hegerogenously licensed" and that you wont release and nobody will see anyway.

Whereas audio/video you generally want to release.

If you make them for your own consumption, then it's my response that rather applies: since nobody will see it, and you don't release/sell/circulate it, you can go ahead and mix Michael Jackson, Disney and Star Wars material - nothing will happen to you.