Yet, 'pure' characters (including the PC) often slaughter demons like animals, even if they are of little actual threat. That's how Kaly view things, and why she does what she does, right or wrong. I'm personally a much bigger fan of muddy grey morality than black and white morality, hence why I'm actually very happy with how Wsan portrayed Kaly.
Imps, left unchecked, rape anything with fertile holes to breed more imps which leads to seemingly endless hordes of them if they aren't culled as much as possible. CoC1, you could find imps everywhere and they were often forming gangs and doing things like kidnapping, drugging, poisoning crops and water, etc. No matter how many of them you defeat or kill, there's always more imps because the world is drowning in imps by that point.
Demons spread their corruption one way or another, regardless of their personal intentions, (or what they claim their intentions are.) No matter how sympathetic and kind the primary antagonist tries to make herself out to be, every race and region she comes in contact with becomes sexually aggressive, territorial, and dangerous to even the natives practically overnight. There's a cult weaponizing the spread of her corruption in the name of power, there's an elven ruler that's trying to turn their entire ancient kingdom into obedient sex toys with that corruption. It's not a question of morality, it's survival and practicality, trying to fight back against a spreading plague of horny-amoral-rape-disease that everyone, the gods, the demons, the residents, and history, all suggest is incurable once contracted. It's like a zombie outbreak, but the zombies are sprouting horns and horse dicks before raping everyone they catch, rather than eating them.
The argument that Kaly is morally grey for joining in on weaponizing and benefiting from nonconsensual bitch-breaking doesn't mean all that much. Her actions put people at risk, she seems perfectly comfortable with that, she's effectively no better than a monster that could end up targeting anyone that happens to end up crossing her path at any time. Sure, survival of the fittest is very much in line with 'nature', but in the name of survival, you'd kill her if you came across her in a game like Morrowind turning people into mindless thralls with musk-magic or whatever and the locals would thank you for saving them from the threat she posed before calling you an n'wah. In most settings, she's just a monster to kill, it's only in lewd games with porn logic that she's a misunderstood waifu who should be appreciated and protected because the genre itself is corrupting the players and their view of the world, normalizing brainwashing and raping folks as something you can justify and rationalize with the right context.
Even just in the most primitive and natural sense, "She is targeting me, she is an enemy, I should defend myself." But CoC2 is an OC glorifying money milking machine, the players are always powerless when a super-duper-special OC is involved. Robbed of agency, and easily upstaged, made a fool of, or deprived of very basic choices whenever an OC is in frame.
That rubs people paying attention the wrong way. I'm a submissive, masochistic even- but this game really sucks all the fun out of it when nothing is ever a personal choice in the narrative. It's all just so blunt and absolute. I'm told how much I adore and admire each individual OC or waifu before they've said or done anything to win me over, the only temptation they've put forth for me to fall for is 'she has a fat horse dick'- her and half the damn region, what makes her special? She smells more than the others? I suddenly have that fetish in-universe? When did that happen?
My tastes aren't important. My consent is never important. I don't get a voice in anything in this game. When playing CoC2, I'm just a vehicle for the individual OCs and waifus to push their own stories and show off. There is no amount of in-universe hard work, willpower, or preparation that can protect me from the narrator deciding things for me. The developers are not on the player's side, many of them are outright antagonistic to the playerbase for one reason or another. They're only slightly more loyal to the people throwing money and free labor their way, so the OCs are given more power than the player could ever hope to over how every encounter shakes out.
TLDR, it's not about which side has the moral highground, this isn't a question of which side is 'more justified' in their actions. It's a fight for survival, and she's behaving in a way that marks her as another dangerous corruptive enemy to be slain- not a waifu to be treasured or romanced. In any other game, she'd be killed shortly after it became clear she was targeting the player character, and her lack-of-pants looted for whatever junk she had on hand when she ragdolled. Because that keeps the player and the rest of the civilized inhabitants of the region safe from evil musk-magicians.