Read my post carefully. My point is that our 19th-20th century laws reflected earlier societal censure against purposeless cruelty and vandalism.
I do understand your point, really. I think societal censure is the only way to stop this kind of sick activity, that's all. The kitten is not a human and our laws were never designed to protect anything but humans and their property from the harm of others. That is the only reason government exists - for humans.