Perhaps I should have spelled out that the definition requires a citizen parent and Rubio had none.
Continued searching turned up this very detailed analysis which supports the alternate point of view.
http://www.constitution.org/abus/pres_elig.htm
I think not only are the waters murky there is nothing to be gained by fishing there. I am convinced that the eligibility issue is a non issue with respect to Rubio after reading this analysis. I am still not happy about birthright citizenship because of the abuses and abuse potential but with the history outlined in the article its going to be a sticky job eliminating or curtailing it.