The Word for World is Forest

Finishing the book, I felt like the last two pages played a very important role in explaining the meaning of the book. Would the Athsheans murder if the yumens had never come to the planet? Or would they have begun to murder if the yumens did not instigate by enslaving and raping? Also, the language used and actions of Davidson portrayed him as a rude, self-absorbed and overtly confident man, who wants to maintain his image of 'manliness', and he accomplished by murdering and raping. For this, the reader looks down upon him, but in a way I feel like the reader roots for the Athsheans once they begin to fit back. But is it moral for them to start murdering? Weren't we already looking down on the yumens for being so careless? And then the Athsheans do the same, to a great degree to protect their land and people. But is it wrong? Is it immoral that they are fitting for this cause even if it is for the good of their kind?