He had the ability to get Canadian citizenship but he never asserted that citizenship. By your definition Donald Trump is never renounce his British citizenship which he is equally entitled to as cruise through his mother.
Except Trump isn't a British citizen. Trump's mother was a naturalized citizen before he was born, to a father who is an American citizen, born right here on American soil.
Cruz is the son of a Cuban turned Canadian who was born in Canuckistan, where no good thing ever comes.