From the foundation's point of view, humans are just as capable of submitting infringing code as AI is. If your argument is sound, then how can Linux accept contributors at all?
EDIT: To answer my own question:
Instead of a signed legal contract, a DCO is an affirmation that a certain person confirms that it is (s)he who holds legal liability for the act of sending of the code, that makes it easier to shift liability to the sender of the code in the case of any legal litigation, which serves as a deterrent of sending any code that can cause legal issues.
If that worked any corporation that wanted to use code they legally couldn’t could just use a fork from someone who assumed responsibility and worst case they’d have to stop using it if someone found out.
It’s just the same as if I copy-paste proprietary code into the kernel and lie about it being GPL.
Is the Linux foundation liable there?
LLMs can and do regurgitate code without the user’s knowledge. That’s the problem, the user has no way to mitigate against it. You’re telling contributors “use this thing that has a random chance of creating infringing code”. You should have foreseen that would result in infringing code making its way into the kernel.
If you don’t feel comfortable about where some code has come from, don’t sign your name.
The fact LLMs exist and can generate code doesn’t change how you would behave and sign your name to guarantee something.