Your issue seems to be with standing. I think Cruz could find a way to get parties with standing. The NBC issue is clearly a federal question and if Cruz were nominated, certainly the Democratic nominee or maybe even the Party would have standing to challenge Cruz’s NBC eligibility. I agree with Trump that almost certainly the Dems would challenge Cruz if he were nominated for President or even VP. The Dems would be stupid if they didn’t and one thing about the Dems, when it comes to political advantage, they are not stupid. It is what they live for.
The problems are not simply STANDING, although Standing is a real tough hurdle to overcome in any lawsuit.
Standing directly relates to being able to show damages that HAVE been done PRIOR to the filing of the suit, not theoretical damages in the future. The Standing issue can only be overcome AFTER someone, Cruz for instance, has damaged the plantiff. That can only be after he is POTUS, not before.
Then comes the Constitution that says that once the person is sworn in as POTUS, he IS President regardless. At that point only Impeachment can remove a President.
That and Standing were two primary reasons none of the NBC suits against the obvious fraud nobama went nowhere.
The other issue with Cruz requesting a declarative judgment on NBC, is that there is no such pathway in our Court system. A suit must be brought by a party, with Standing, first.
Being a very astute Lawyer and Constitutional scholar, why would Cruz ever want to defy both law and the Constitution by not defending both from an illegitimate suit brought by anyone with no standing?