It doesn’t matter if Cruz (or whoever) is a natural born citizen. There is simply no way to enforce this particular clause through the court system. Such scenario have been played many times with the current President. If you sue Cruz before him being elected President, you have no standing. If you do it after that (when majority of electorate votes for him), you’ll find no judge (SCOTUS included) willing to overturn the will of the people. It is a waste of time, in my opinion, and a waste of bandwidth...
Yeah, except everything you described only applies to democrats. A conservative Republican is fair game, with a red lazer-dot on his forehead.