IIRC...they aren't union so it will be much easier.
Then they can all go scatter out to the K Street lobbyist firms and Sunday Morning talk shows they all long to be on.
Yes...they serve at the POTUS' pleasure.
I think he's already signed an EO having as much as a 5 year wait before you can lobby. And, I'm not sure being ex-State Dept...employees, etc., that there's a gag rule.
The previous administration went after whistle blowers with a vengeance. I don' think they're going to screw with Trump.