this is actually a situation i've never had a chance to write with damian which is funny because he usually is the voice of like "well maybe this dubiously ethical thing isn't so bad." and needing "basic human morality" explained to him. the problem is that in most games, he's actually way more morally driven than most of the rest of the cast.
he believes killing people IS BAD. he's had several arguments about this with people who think that makes him weak. this is the first time he's presented an idea that he thought was morally completely sound and in line with what is acceptable for a hero to do and being met with suspicion, doubt and horror from people who (from his perspective) immedaitely
he regularly resorts to terror tactics, beating prisoners, psychological warfare, threatening to kill people, kidnapping, throwing his weight around to seize control of a situation, manipulating everyone around him, using other people for his own ends... by the standards of most people he's a total nightmare. in universe and out of universe
this isn't a case of bad writing he's been characterized this way since the early 80s. and he's also damian's best moral reference for the most part. him or dick grayson, but damian hasn't even spoken to dick in months.