It remains to be seen that the concept of ethics is "intrinsically bound" to concept of altruism. In order for this to be true, there could be no scenario in which both "X acted unethically" and "X acted out of altruism" could simultaneously be held true. But examples of this are simple to form. For example: John committed a violent robbery in order to give the money to starving orphans. Judgments may vary, but it is certain that at least someone could make the ethical judgments "John acted unethically" and "John acted out of altruism".

I have many other disagreements with your notion of "cultural evolution" but since post is supposed to be about Kitcher, I will only say that, as it is, his more tentative definition seems much more reasonable than yours.