http://www.heritage.org/constitution/#!/articles/1/essays/40/naturalization
Now, where's your source that says Congress's naturalization powers apply to "natural born Citizens?"
My source is Article 1 section 8 and in addition to the clause about creating the rules for naturalization, the final clause of section 8 reads:
To make all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this Constitution in the government of the United States, or in any department or officer thereof.
In addition, your cited reference from heritage, you apparently forgot to read the paragraph that starts “In Rogers v. Bellei (1971), however, the Court did uphold a statute requiring that if a person acquires United States citizenship by virtue of having been born abroad to an American citizen,...” That clearly shows that SCOTUS believes that 1) A person can acquire US Citizenship at birth though born abroad and 2) that citizenship at birth only requires one US Citizen parent.
Now as to your first citation. Please take the effort to look down on that page and find the URL “Citizenship Through Parents” and follow that link. Then look down to left hand side to the third case (Mr Cruz was born December 22, 1970). IN YOUR OWN CITATION, The parents are married at the time of birth and the U.S. citizen parent was physically present in the U.S. or its territories for a period of at least ten years at some time in his or her life prior to the birth, at least five of which were after his or her 14th birthday.
Mr Cruz’s mother was a US Citizen, attended college in Texas and graduated with a Bachelors. It therefore follows that Mr Cruz acquired his citizenship from his mother at his birth and as such, has never need to be naturalized and is therefore, a natural born citizen.