-- No, this situation would have arisen in any case, because you cannot force everyone to obey your law. If you use force for this, you will have to use force against your own allies, and in the end, you will have fewer, not more. You won't be able to persuade those who don't want to be persuaded, and you will lose your own people. And if you try to convince them with arguments, you will hardly find many fools who will sacrifice something when they can avoid it and do the same thing. Even if you convince most people, the remaining ones will drown humanity in blood, because my example about thirty friends is absolutely true to life; it is precisely about that. It only takes a few lawbreakers to ruin all your fantastic plans, even if you can fantastically imagine everything else.
-- Another problem is heresy. You understood the law correctly, but someone else will understand it in a way that benefits them. You won't be able to accuse them of anything, because outwardly, they comply with everything, but they kill indiscriminately, but is that forbidden? And he will plunge your society into chaos.
-- Here is another law of balance: an eye for an eye, a tooth for a tooth. What's wrong with that? Everyone gets what they deserve; if someone harms you, you do the same in response, commensurate with the crime. If your comrade is killed, you kill the one who killed him. Without any exceptions or concessions, everything is strictly enforced. In theory... criminals should not commit crimes in this case if the law is strictly followed, right? At the same time, you don't need to make difficult moral choices; this law is intuitively clear and simple to everyone, and it would be much easier to accept than yours. And, it seems, it was actually in use somewhere for some time... I don't remember now. But, as you can see, it's still relevant.
-- So, in reality, alas. All these "what ifs"... "What if I were a queen, and what if everyone obeyed"... The only reality available to us is the one that is before our eyes. And since that is the case, your ruler, who somehow became a follower of the Law of Balance, is either the only one or one of the few, and the first war destroyed his country. That's it. No fairy tale came true. This is not reality, but it is much closer to reality than anything you can imagine.