My response to you is, Eh. I understand WHY the humans killed them. It makes sense. But I can understand someone's actions and motivations without -agreeing- with them. I can also understand why the RAS used Scarlet Crusaders to test the Blight. Doesn't mean I agree with their actions or think it was appropriate.
As to the people leaving: They didn't ask, or at least it hasn't been shown, yet. It's been shown, canonically, that if you ask you can get released from your promise of service. It's never been shown that someone asked and was denied.