Read up on it. The only party with “Preventative” Standing is the government and that is very narrowly defined mostly to criminal activity and environment.
“Honestly, why would the Constitution have an NBC requirement if there was no way to prevent a non-NBC candidate from being sworn in?” That indeed is a $64,000 question.
My assumption is that they were concerned right after the Revolution about some Loyalist being able to get elected and sliding us right back to King George. By leaving NBC undefined and beyond natural citizenship, they could “define” by decree, “it” as a case made it necessary and deny any person as they wished, NBC for POTUS purposes.
If NBC was such a big thing they saw in the future, why did not they intentionally leave it both undefined and aside the normally recognized natural citizenship? Simply put, once that generation and immediate Loyalists were gone the need ceased and regular natural citizen is the definition they choose by abstention.
Well, again original understanding and intent is the way we should be interpreting the Constitution when the meaning of the text is not plain. Your reasoning may be correct, dunno. But this is a constitutional requirement that obviously should be answered before the candidate in question is pronounced President. Original intent would require this if there is a genuine dispute which there is here.
Precedent has to start somewhere and I think there is strong argument for this issue to be decided in a federal court one way ot the other. This could very well add “constitutional eligibility for President” to states issues, criminal, and environment for “preventative standing”. It is an exception, like an appeal from an objection that is allowed during a trial if the lack of a decision can’t be changed later and irreversibly affects the outcome of the trial.