> Under this EO, the agency wouldn't comply, since the agency would assume Trump's read of the law is correct - superceding even the Court's. If they tried to enforce a contempt order, the US Marshals would not comply either.

Why? The Marshals enforce blatantly wrong court judgements all the time. Court judgements are court judgements, contempt orders are contempt orders, both can say almost anything. There's no interpreting the law part of enforcing a judgement or order - the court judgement is just as valid whether it's legally correct or not.