No comment on what Kogane did since we don't have enough info.
I do think the little speech about human greed is uh... not very well reasoned, given the greed we've seen from non-humans in this manga and also what I've seen real animals do. I have a family member who adopted a cat who was literally starving to death... then found out another family was putting lots of food out for the cat, but the cat's own sister would bully her and eat all the food every time, and she was big and healthy from eating all the food meant for two cats. What is this if not betrayal for greed?
Sorry for depressing anecdote. I just have very little patience for the humans are the real monsters, nature is a noble savage, and similar memes. We already know what it looks like when an animal evolves to a higher state of existence and gets sapience and some kind of morality. It's us. Our forebears were apes. A fox would not be better.
edit: Unrelated, but imagine the lack of foresight it takes to be a malicious plant creature and have no plan for dealing with getting set on fire. At least do stop-drop-and-roll, and have ya boy toss some dirt on.