Not a fantasy at all. There’s tons of Supreme Court case law over many years against Cruz. Cruz knows it, and anybody who has read the case law against Cruz knows it.
And about the Standing Doctrine you can read about it here.
http://www.freerepublic.com/focus/news/3396293/posts?page=231#231
And here too.
http://legal-dictionary.thefreedictionary.com/Standing
I love how Trump supporters are both legal scholars and Trump speak translators. It must be too expensive and bothersome for Trump to actually hire a professional lawyer to file suit in court and to make legal arguments on his behalf.