That's the fallacy, in a nutshell.
There are several statutes that convert a person who otherwise would not be a citizen, into a citizen, merely by the circumstances of birth meeting the conditions stated in the statute.
In order to be naturalized, one's citizenship must depend on an Act of Congress. That's awkward phrasing, but that's a form of definition for "naturalize."
Please explain further. My initial reaction is that a statute isn’t really the constitutional standard its would just be another way to naturalization. So maybe there is a way to be de facto naturalized without taking any affirmative steps, but how does this bear on Cruz? Is he naturalized? I doubt he would be out there if his paper trail let to a document that said he was naturalized.