Originally Posted by
shinta|hikari
But if the soldiers decide to not do it, they will be killed for not following orders. Even if they wanted to commit genocide, a moral person wouldn't just pre-emptively (or even retaliatorily) murder them all. There are other methods available to someone as powerful as Rimuru, such as convincing them to stop through a show of power (blow up a mountain) or assassinating their leaders to minimize loss of life.
The key thing here is Rimuru didn't care about doing the right and moral thing. He just wanted to resurrect his people (which I cannot fault him for). Sacrificing thousands of lives (that can be redeemed, people change) to revive a few of his friends and comrades is NOT moral and not something a just person would or should do. It is definitely understandable, but it is not morally justifiable in most human paradigms.