That's easy. Two reasons:
1. You didn't get my 'A' and 'B' example in the other thread, so I'll make it more concrete. Let's say the question is whether someone lives in Texas. If I spend hundreds of words demonstrating that they live in Houston, I'll still end by saying "and therefore she lives in Texas" because that was the question asked. It doesn't negate the fact that my whole proof of that was based on their living in Houston; similarly, the fact that the court concluded by saying that WKA was a citizen doesn't negate the fact that there whole reasoning was based on demonstrating that he was a natural-born citizen...
2. ...a fact the dissenting judges recognized. They wrote, "it is unreasonable to conclude that 'natural-born citizen' applied to everybody born within the geographical tract known as the United States, irrespective of circumstances." They wouldn't say that in the dissent unless they recognized that in fact that was what the decision meant.
Was it asked "Is Wong Kim Ark a natural born citizen"?
No
Did it affirm "Wong Kim Ark was a natural born citizen"?
No.
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The continued assertion is that the court proclaimed him a natural-born citizen is false.
All of the 'rationale' reasoning' and 'examples' in the world are moot because none of them can change the words contained the final determination.
Wong Kim Ark was a 'citizen of the United States'.