The fact they're Turing complete isn't really getting at the heart of the problem. Python is Turing complete and calling python "intelligent" would be a category error.
It is getting to the heart of the problem when the claim made is that "no matter how advanced the model" they can't be 'much more than just "really good autocomplete."'.
Given that they are Turing complete when you put a loop around them, that claim is objectively false.
I think it'd even be easier to coerce standard autocomplete into demonstrating Turing completeness. And without burning millions of dollars of GPU hours on training it.