Bellei lost his citizenship due to a State Department interpretation of the Immigration and Naturalization Act that was upheld by the Supreme Court and later rendered moot by subsequent legislation.
That subsequent legislation was passed before Senator Cruz was born.
Bellei visited the United States under his American passport in 1948, 1952, 1955, and 1962. His last trip was made in 1965 on his Italian passport.”
Senator Cruz, on the other hand, has been permanently domiciled in the USA.
You seem to be purposely blurring the point. These two cases still hinge on statutory law and not on natural law as the Supreme Court used to exclusively define natural-born citizen. It doesn’t matter that Cruz had permanent domicil; he was not a natural citizen at birth.
How do I lose my citizenship?