Congress received certified EV from the states. If those for Zero are nullified for being cast for an ineligible candidate the state does not get a do over. Congress must choose from 3 candidates who have received certified EV and that would be McCain, McCain or McCain since he is the only one to have received EV.
Our Founders did not anticipate mass national parties taking control of the process which limits the number of candidates who actually receive EV.
Not yet they haven't. The electors have not yet gathered in their respective states to cast those votes, and the talley sheets/certifications have not yet been sent to the President of the Senate.(Aka Vice President Richard Cheney)
It would be quite amusing to watch the Veep open the certifications, and say: "Alabama, 9 votes for John McCain, Alaska, 3 votes for John McCain, Arkansas 6 votes for John McCain, Arizona 10 votes for John McCain, California 55 votes not cast for an eligible person, Colorado 9 votes not cast for an eligible person" and about then All Hell would Break Loose, first in the House chamber, and then all over the country. While VP Cheney just continued, unperturbed, "Connecticut 7 votes not cast for an eligible person.... " :)