Although justifiable in few aspects, Ender's actions were ultimately uncalled for in the situation and therefore should be punishable. As said in the texts of warfare Ender studied, "It was forbidden to strike the opponent who lay helpless on the ground; only an animal would do that" (Card 7). After Ender knocked Stilson down or had been let go by Stilson's posse, Ender could have easily made a run for it and called for authorities. Instead, Ender violated this particular law of warfare and, according to the book, also violated his own humanity. Through his actions, he proved himself to be no better than the bullies nor Peter - something Ender realizes when weeping in the bus. Colonel Graff dismisses this, implying that a lack of compassion would be key to winning battles. However, if a lack of compassion was present, then it absolves one of his humanity. And by definition from the book: that would make this would-be soldier an animal.