There are two possibilities. Haley's parents either were naturalized citizens when she was born, or were in the process of becoming US citizens when she was born. In the first case, the children born of legally naturalized parents are NBC like all other second generation children of legal immigrants. In that case, legal filings claiming she is not a NBC are falsehoods that will get thrown out of court until the courts are tired of a lawyer making a fool of himself.
If her parents were in process of becoming citizens when she was born, US law and court practice treat children born of naturalizing but not yet naturalized citizens as NBCs. They are not citizens of their parent's home countries, they were born on US soil, and US citizenship is governed solely by US law, foreign citizenship law has no bearing on US citizenship law. There are only two types of legal citizens, NBC and naturalized. There is no other citizenship categories. Period. Full stop on no other citizenship types.
Short version, as I understand it, allowing the children born of naturalizing citizens who become naturalized citizens, while they are becoming naturalized citizens to be NBC, keeps the law and legal process simpler and usable. It also prevent creating a third type of citizenship which does not exist under US law or have any precedent in the courts.
I hope this makes some if not complete sense. Immigration and citizenship ship law is has a particularly messy history.
Thank you.