Which judge ruled on his case? I can’t seem to find it.

They didn’t. No ruling exists. This dude was just black bagged.

It's not based on legal precedent, it's right in the code. It was part of the "Immigration and Nationality Act", which most people refer to as "INA".

You still need a judge to rule that he in fact broke the law. (Specifically an immigration judge.)

Misread "his" for "this". He's only just been detained, I don't imagine a hearing has happened that fast.

Then he still has green card status.