If both his parents were LEGAL residents in United States, and if Rubio was born on US soil, then Rubio is NBC based on precedence set by Obama. And Rubio’s birth certificate is not secret, unlike Obama’s which was kept under wraps until Trump made a big stink about it. Many experts have opined that the Obama BC is manufactured. Not so with Rubio’s BC.
Obama can’t set “precedence.” There’s no such thing as precedent in American Constitutional law. (You are thinking of English law, where there is no written Constitution.) What matters is the text, as it was understood by those who wrote and ratified it. And according to the text, as it was understood by those who wrote and ratified it, Rubio is not a Natural Born Citizen because his parents were not citizens when he was born.