No. His claim is:
>>>> If you're not the author then why would you have to be liable for it?
And all his arguments after that are to support that claim. His claim is wrong.
Ownership and liability are independent of each and all his supporting arguments are dismissing this fact.
> Whoever did create the car/boulder is not liable for what happened.
Incorrect; whoever owns the car/boulder is not liable. The creator doesn't even enter this argument.
> So whoever made the LLM is not the author but the one who used it to create the code.
No; whoever created the LLM is irrelevant. The author who creates the code is similarly irrelevant. What matters in his argument is who owns the code, and this is also irrelevant to his argument, because ownership does not mean liability.