Nobody is talking about revoking Cruz’s citizenship. The only point made by the existence of Rogers v. Bellei is that Cruz, like Bellei, is a naturalized citizen.
It should be easy then to get a copy or a confirmation record of Senator Cruz’s Certificate of Naturalization, which is a publc document available under a Freedom of Information Act request.
Even President Chester A. Arthur’s father William’s Certificate Of Naturalization from 1843 is still available for viewing.
https://naturalborncitizen.files.wordpress.com/2008/12/william-arthur-naturalization.pdf