There is a body of common law on citizenship, that stands separate from statutory citizenship law.
The reason I asked if you read the case, is that the case says that a person who is born a citizen, where citizenship depends on a statute, is naturalized, even though that person has no need to go through a naturalization procedure. that what the case lays out as principles of law, in those terms.
I assume you disagree with the court, which is fine. The court may well disagree with itself if it decided the same case next week. The court picks outcomes depending on the parties and outcome, not on the law.
Common law is secondary and subordinate to statutory law.