Let's imagine for a moment that the Organians are exactly what they have portrayed themselves to be: a defenseless pre-industrial society. A stronger, militant power attacks, intent on conquest and occupation. The Organian leaders, opposed to using violence, refuse to resist this invasion in any way. Meanwhile, a third party- a rival of the invaders- offers to to help them defend their land and people. Not only does the council refuse this help, it condemns those who offer it as no better than their attackers, because they advocate the use of violence. Inevitably, the invaders take their planet and enslave their people, instituting martial law. The council not only refuses to stand against this oppression, but actually promises their new overlord that they will not oppose him in any way. And then, as this dictator begins rounding up civilians and summarily executing them, the leaders sit cozy and untroubled in their council chamber, making no effort to stop this atrocity from happening. Does this still seem like the noble option? Is this really the more enlightened approach: remaining passive while the blood of your people runs in the streets? Take away the Organian's immortality and their behaviour goes from being noble to being criminally negligent and complicit. Since the Organians refuse to descend from their high horse and let Kirk in on their little secret, this is exactly what he thinks is happening. In my opinion, this completely justifies his contempt for leaders who would betray their people in such a way.
When Kirk states, "We have the right-" Ayelborne interrupts to ask, "To wage war? To kill millions of innocent people? To destroy life on a planetary scale? Is that what you're defending?" Shocked out of his anger, Kirk fumbles for an answer, "Well, no one wants war..." which is mostly true: no sane person wants war. But my reply to this question would be: yes, we do have the right to wage war. Every freeborn person has the right to take up arms and defend their home, their family, and their freedom from evil people who would seek to destroy these things. And if you're a member of something like the Federation, this is not only a right, it's a responsibility. What are the selling points of being in this sort of alliance with other nations- or in this case, planets? There are of course cultural benefits- the exchange of ideas,etc- as well as economic ones, facilitating trade, the sharing of technology, and that sort of thing. One of the main benefits, however, is mutual protection. When one member of the Federation is threatened by an enemy- like the Klingons- the other members are duty bound to come to its defense, providing strength in numbers. We have it on good authority, from both Kirk and Kor, that the Klingons have been attacking Federation planets, killing some citizens-