Read it carefully.
The case involved whether he should be released from custody. The judge ruled he should be released. There's sufficient evidence to believe he's a citizen, coupled with everything else, he's not a flight risk or a danger.
But the judge didn't rule him a citizen. That's more of a determination by other courts. Even that court didn't find he was a citizen. Not that court's job.
He was born in Nogales, Mex. That's immediately a problem, but if you're born to a US citizen living abroad you're a US citizen and regularizing your status is something you can easily do. But it's something you need to do. We like government. There's a process for this.
Except there are restrictions on who can claim citizenship, but I'm sketchy on them. The father or mother must have been present in the US for so many years in some time period prior to the kid's birth, I think it was. They recently changed as the result of court order--the time period was greater for the man than for the woman, somebody claimed this was sexist. The result was that the time period for the woman, if I recall correctly, was increased instead of the time the man had to be resident in the US decreased, so the guy lost his case and it became *harder* to have birth abroad as ground for citizenship. More equal, but harsher.
And you still have to provide evidence of paternity, if citizenship's claimed through the father's line. And submit evidence of who's your mother, too. In other words, you're not assumed a citizen until proven otherwise.
In any event, citizenship isn't automatic, as is when you have a US birth certificate. He hasn't done this, or the immigration/naturalization court with original jurisdiction hasn't ruled. So there can be sufficient evidence for a court to order him released but until he actually regularizes his status his citizenship isn't acknowledged.
= new reply since forum marked as read