After doing significant research into the issue of eligibility as per the U.S. Constitution, I have found NO case law or legislative reference which defines NBC as per eligibility for POTUS. The most that I’ve been able to find are references to nebulous requirements relating to allegiance of the parents to other countries or states other than the U.S. at the time of the birth of the person in question. I also found reference to a person, born in the U.S., becoming a NBC at the time their parents become a naturalized citizen - this would be after the birth of the person in question. Since Rubio’s parents became naturalized citizens shortly after his birth, the question of Rubio being a NBC is settled. Those SCOTUS cases involved issues not related to the topic at hand. Since there are two precedents of Presidents having held the office of POTUS without having parents who were citizens at the time of that person’s birth (President Arthur, President Obama), I’d say these four SCOTUS cases are meaningless in answering this question. SCOTUS has not issued a ruling for any case as of this time regarding this issue. Until they do, there is NO case law which makes Rubio ineligible. Nor is there any legislative law.
Ok, that settles it then. (....backing away slowly....)