If you fire them all, you will certainly get some good ones, but you will definitely get all of the bad ones!
I feel just a little squeamish about firing the good ones, but I'm still okay with it. The good ones can get jobs elsewhere easily. The NSC has (or should have) lost the trust of the President of the United States and of the American people.
This is a very large swamp; we're going to need the biggest drain available if we want it cleaned up.