You are correct. The Supreme Court has already established that to be classified as a "natural born citizen", both of your parents must be citizens at the time of your birth (Minor vs. Happersett). Rubio does not meet this standard and cannot be eligible to serve as Vice President or President. The preservation of our Constitution is far more valuable to any one of us than any candidate we might wish to have elected.
I think you’re citing the wrong case. At least according to Wikipedia:
Minor v. Happersett, 88 U.S. 162 (1875), was a United States Supreme Court case in which the Court held that the Constitution did not grant women the right to vote. The Supreme Court upheld state court decisions in Missouri, which had refused to register a woman as a lawful voter because that state’s laws allowed only men to vote.