Daru's plight is paralleled with France's difficulties and Camus' own sensibiities. In the story we see Camus' concern regarding the political situation in French North Africa. Daru's refusal to bear arms or follow orders from the military are related to the dilemma for those who refused to take sides in the war in Algeria. (Camus was strongly attached to Algeria and did not want to see it separated from France.)
The story is not limited only to this situation, but to how Camus saw the world. He did not believe that life was useless and without purpose as some people did at the time. It would seem as if the Arab had adopted this philosophy: that without purpose, his life had no meaning. Without knowing what he would do if he escaped, he chose, instead to go on to the jail, for at least he saw the purpose of this: this was the goal of his trip, what he had been expecting and preparing for.
Camus would not have respected this kind of behavior. He believed that life was important to live, regardless of what it demands of the man.
We learn from the story that making the moral choice is always the best choice, however, it is not always rewarded. Sometimes goodness is punished and evil extolled. In the story, Daru makes the moral choice to defy convention and help the Arab. His goodness is not rewarded: the "guest" refuses his help, and the Arabs leave a threatening message for Daru on the chalkboard.