Elected officials set policies. Government employees implement those broad policies into action. You can change the policies your representative is pushing by changing the representative. I'm a little unclear on where exactly the FBI director falls (because he's appointed to his job with the advice and consent of the Senate, which makes a difference for these things, maybe). A FBI field office head chanting "locker up" in a press conference would be violation though, yes.
The First Amendment distinction here being what, exactly? The President can chant "lock her up" but it's a violation if their FBI director does it?