Remember that the Khmer Rouge were playing hardball. They would have taken them one way or another.
Let's not jump on the French foreign service after they had just witnessed the American foreign service cut and run like dogs.
I still think it's wrong. The French delivered him to certain death and they knew it. Would the Khmer Rouge have invaded the French Embassy to get one man? Possibly, but that is an act of war and the French should have stood their ground.