Please direct your question to the 98 eminent Senators of the U.S. who incorporated this definition in their Senate Resolution 511.
It does appear that the the senate passed a resolution which incorporated a definition in which both of one’s parents must be citizens of the U.S.; NOT that both of one’s parents must be “natural born” citizens of the US.
I’m still not sure they are correct, but there is a BIG difference between the two definitions. By the definition posted in the original article (in which it was stated that BOTH of one’s parents must be “natural born” citizens) it would be impossible for ANYONE to be a natural born citize of the U.S.
However, even with that said, senate resolutions of the type you mention are NOT legally binding. Only the Constitution and the CFR contain our laws.