It’s not about the mechanism: responsibility is a social construct, it works the way people say that it works. If we all agree that a human can agree to bear the responsibility for AI outputs, and face any consequences resulting from those outputs, then that’s the whole shebang.

Because contributions to Linux are meticulously attributed to, and remain property of, their authors, those authors bear ultimate responsibility. If Fred Foobar sends patches to the kernel that, as it turns out, contain copyrighted code, then provided upstream maintainers did reasonable due diligence the court will go after Fred Foobar for damages, and quite likely demand that the kernel organization no longer distribute copies of the kernel with Fred's code in it.