But did the judge make the decision? I think there's a real question of whether this is a failure of due process rights. But I also think supreme Court Justices need to be awake for the court to actually hear arguments, so what do I know.

That is what the article and judgement was about- they can certainly use that argument to appeal the case, but not to hold the judge in the case personally liable.

The judge did make the decision to outsource to an LLM. This isn't new and isn't too different from tossing a coin.

IANAL, but my understanding is that Judicial immunity in the US is absolute; if a Judge orders the police to beat up a defense attorney, they cannot be sued for it[1].

1: https://en.wikipedia.org/wiki/Mireles_v._Waco

There would be a real question if the judge in fact used AI. The plaintiff's complaint (https://storage.courtlistener.com/recap/gov.uscourts.nvd.176...) makes it pretty clear that he's just nuts and had no real reason to think she did.

But of course a court can't dismiss someone's complaint on the grounds that they're nuts; in order to rule on the substance of this case, a court would have to conduct new hearings to gather all the details about the original hearing in which AI was allegedly used. The purpose of judicial immunity is to push all objections to judicial decisions through the appellate courts, which don't have to re-hear everything before issuing a ruling.

either the judge made the decision (in which case he has immunity) or he didn't (in which case he isn't the right person to sue)

the correct steps are appeals in the merit and disciplinary action against the judge