Apparently, there's an avenue through which State Department employees can express their disagreements with management, and some employees have used it. See Report: About 900 State Dept. Officials Sign Dissent Memo on Executive Order. That's all well and good so long as they don't fall into passive aggression mode or otherwise attempt to thwart the boss' orders. But this from Sean Spicer seems apropos: "I think that they should either get with the program or they can go."
And this is not good either: 180 federal employees sign up for 'civil disobedience' class.
There are probably plenty of qualified civilians available to fill those positions. Civil service reform is long over due.