If I, in working for someone else, ever came to the point where that ultimatum was issued, it would be because of a serious disagreement between the employer and myself over what constitutes the ethical discharge of my duties to him/her. I'd have him fire my ass, because I'd have the documentation in hand of what led up to the firing as I walked out the door. I'd have no problem telling my next potential employer that I had been fired, why the boss fired me, and then showing him my documentation in support of my position.
But then, I wasn't the HNIC when nuclear weapons and fuses for nuclear weapons made unauthorized trips TDY when under my responsibility, either.