I have had my share of disagreements with Dr. K but he is a very astute observer and analyst. He is rarely wrong in his assessments.
And nothing is DONE when murder is involved.
As much as I would like to see the administration prosecuted for such and believe that they are morally responsible for the murder of the Benghazi 4, they did not commit a legal crime. They are guilty of malfeasance and dereliction of duty resulting in the deaths of 4 Americans, but even the best prosecuter would be hard pressed to get a conviction of murder. Diplomatic misconduct would be the only thing that they could be tried on, but according to the Constitution, they are immune (US Const Art 1 Sec 6) unless in the case of felony, which would be a stretch.
With regard to any diplomatic misconduct, Dr. K is correct, the clock has run out. The only thing left would be to go for impeachment AFTER Republicans take the Senate and retain the House.
Believe what you want.