I am not an expert on how the SCOTUS works but if a case is to be heard would it be because the law is not clear in the case before it. In other words if NBC is settled law, ie Minor v Happersett, then would not the court just refuse to hear it? (As it has) Do they need to tell us “Hey look at Minor for your answer....?”
They DID tell us to look for Minor for an answer to how NBC is defined. That definition meant they needed to look at other criteria to determine whether or not WKA could be declared to be a citizen. Here's the question that Justice Gray said was before the court:
The question presented by the record is whether a child born in the United States, of parents of Chinese descent, who, at the time of his birth, are subjects of the Emperor of China, but have a permanent domicil and residence in the United States, and are there carrying on business, and are not employed in any diplomatic or official capacity under the Emperor of China, becomes at the time of his birth a citizen of the United States by virtue of the first clause of the Fourteenth Amendment of the Constitution,All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.
In Minor the argument about being a citizen by virtue of the first clause of the 14th amendment was rejected because Minor fit the NBC definition. In the latter case, WKA does NOT fit the NBC definition, so it is left open that WKA can be declared a citizen under the 14th amendment, providing the birth and subject clause could be satisfied despite a Treaty that would suggest he could not be a citizen of the United States. Minor gave AN answer, but it did not give THE answer ... which was ultimately based on separate and distinctly different criteria.