It's a crime to harbor or aid illegals in evading federal authorities. So this is a legal obligation of every person.
(It's not a crime to aid illegals if the authorities don't have a valid warrant.)
So the judge is no more "obstructing justice" than if I refuse to open the door to let ICE agents in to arrest someone with an administrative warrant, and then that person leaves out the back door.
ICE should have obtained a judicial warrant, but they didn't. That's their fault.