This short story is very reminiscent of the ancient tradition of gladiator fights and justice dealt in arenas. The text proclaims the king to be "barbaric"--he always has to get his way. Typically, someone considered a barbarian is uncivilized, and any form of justice would be considered primitive. In this story, this barbaric king believes that he has developed the best form of justice: he will put the accused in an arena and allow him to choose between two doors, one hiding a lady and one hiding a tiger. If the accused chooses the door with the lady, he is innocent of the crime and will marry the lady. If he chooses the door with the tiger, he will be considered guilty of the crime and eaten.
There are many things at work here. The punishment of being eaten by a tiger is barbaric, and allowing the accused to "choose" his fate leaves the king blameless. The king believes this is a perfect system; he is a barbarian who believes his system elevates him.
The author is mocking the belief that bad things happen to bad people, or that "karma" will correct the issue. If the accused is guilty, they will choose the door with the tiger--it's like fate.