The interesting thing about the king in Chapter 10 is that he is completely incapable of either passing a reasonable law or upholding any unreasonable laws. Every decision he makes is formed with the intent of pacifying his subjects; however, he really has no subjects. He is really king over no one. There are probably many public figures we can accuse of making decisions with the sole intent of pacifying others; however, literary critics have actually considered the king to be a reference to the French government just prior to and during World War II, particularly acclaimed French World War I general Henri Philippe Petain who governed France during Nazi occupation.
Once France surrendered to the Germans as soon as 1940, the Nazis established a new French government in Vichy that was run by Henri Philippe Petain. It is noted that the French allowed the Germans to plunder their resourced and even agreed to sending French citizens to Nazi labor camps. Prior to France's surrender, France, along with Great Britain and Italy, signed the Munich Pact, allowing Germany to invade Czechoslovakia, with the intention of pacifying the Germans. France's early surrender can also be seen as an effort to pacify the Germans. In addition, it is said that they allowed German occupation because they "hoped to preserve at least some small amount of French sovereignty" ("France History -- France during World War II"). Since all of France's political moves, especially under Henri Philippe Petain, were aimed at pacifying Germany rather than creating any real sovereignty for themselves, we can easily see how the king in Chapter 10 directly reflects France at this time period.
Saint-Exupery was a pilot in the French Air Force during World War II and was sent to the US with the intent of convincing the US to enter into the war against Germany ("Biography of Antoine de Saint-Exupery"). As a French citizen and a member of the French Air Force, his government's actions would be very important to him. Hence, it is not a stretch to interpret the king as being representative of France or of Henri Philippe Petain in particular.