This is very interesting question and still we can see the Chinese culture inside. "扒绝户坟" is translated into "dig the grave of a family without offspring" and the translation might be correct. Digging the grave is the worst and forbidden behavior in Chinese culture. But why grave of a family without offspring? The meaning behind is the same as other sentences – not to bullying the weak one. If you dug a grave, which has family and offspring, they will come and find you. But if there’s no, you are bullying the weak one. “吃婴儿的奶” is translated to “drink the milk of a baby” and it is not correct. It should be “drink baby’s milk”, yet it is also the same just not to bullying the weak one. And why these things exactly? Is it from literature? Or some proverbs/traditions? Or is it just an invention of the film director? I cannot make sure the originals but it reflects the moral principle of Chinese people.