You’re forgetting (if you knew in the first place) that judges get lifetime appointments to the bench. They may be impeached, but they can’t be “fired”. Even if they could be, Trump does not have the power to do that. He is not and never was their “employer”.
You seem to be parroting a standard that most liberal judges would agree with. What is the point of giving someone a job if they are not going to look out for your best interests?