Well to be clear I don't think the author meant to classify the Tamils in enemy areas as the 'enemy' but rather the 'enemy side'. He meant it in a geographical sense. With respect to comparison with other historical cases, I believe the author does clarify that in a way when he said 'whether civil war or war between nation states'. Your French example is one where the war was between nation states. Therefore in the case of occupied France, there was no French government to supply their people. It would have had to come from the Allies. The same would have been the case with the Nazis. There was no other German government to save the Hitler youth from being brainwashed and recruited. Again that task was also left to the Allies. Vietnam? well that is a whole different game. Was it really a civil war or was a it thinly disguised war between the US and China / Soviet? Whatever.
Nevertheless, I agree with the author that rarely in history has the government in civil or national conflict has taken too much direct interest in the welfare of the civilians residing on the side.