Cruz can argue that Obama being allowed to be POTUS in spite of legal confirmation that he has no legally-valid US birth certificate sets a precedent for a foreign-born person to be POTUS.
Then by the same logic Presidents 1 through 43 are precedent that offering a birth certificate isn't a necessary condition for the Presidency in the first place. That argument goes nowhere.
In a case where Ted Cruz is the defendant, NO judge anywhere is going to entertain any party trying to talk about Obama -- who isn't a party to the case. It's irrelevant.