honestly i get what you intended with this explanation but i doubt the moral gymnastics of a vampire really matter. Tbh based on what I've read and on the raws alone the plot is pretty uninspired as it relies on a plethora of stereotypes and cliches with the sprinkle of mpreg for those screaming fujoshi in the back, I doubt author honestly has time to consider the philosophy and ethics of killing through the eyes of a mythical predator when there's age old tropes to uphold in the name of vampiric/ lycan babies.
Of course they don't, vampires aren't real (as far as we know). But i'm not discussing the possibility of vampires in reality and their theoretical morals, i'm specifically discussing the stereotypical fictional vampires found all over the place in literature and the cliche line present in this manga said by most of these types of vampires to the point that it's a cliche. You must've thought i was talking about reality because i mentioned humanity irl, but humanity in literature is based on irl. If i read about a farm in manga, i'm going to assume it works like a farm irl as there are farms irl. Vampires have no basis in reality, but humans do. Basically, i wasn't comparing these fictional vampires to irl humans, i was comparing these fictional vampires to the fictional humans under the assumption that they act as we do.

In the 1st place, humans don't "kill each other" for FOOD, then there is the flawed argument of comparing humans hunting animals to hunting humans as humans are entirely more sentient. Not to mention that in the majority of these types of stories the vampire has no concern whatsoever for human life while as humans empathize with their food when the subject is broached. The lack of empathy he just showed at the prospect of ending a human life with people who think and care about them was on par with that of a murderer, rather than someone just doing anything they could to eat. Was he going to even leave that girl alive? He laughed while explaining to our MC that he just ruined his life and straight up said it was a burden as he "no longer needs him". Don't make a mistake, he did ruin his life, it's going to be much harder to acquire food as the vampire admitted just now as they have to eat "in secret". What he essentially just did is equivalent to a human drugging an animal, taking it's leg for food, cauterizing the wound and then letting it back out into the world... It's literally just... Harder to eat now. Sure, you can make parallels between this type of vampire with the darkest parts of humanity, when humans HAVE to do whatever is necessary, but i fail to see how that's even a valid argument when the average human doesn't walk around disassociating while killing humans (or in our case an animal with equivalent self awareness and intelligence) for food... I believe the closest animal to our level of self awareness and intelligence would be apes and those are illegal to hunt, most likely because there is a moral argument to be said for hunting ANYTHING past a certain level of self awareness and intelligence... ╮( ̄▽ ̄)╭
The difference is that the "prey" isn't the same. Anyways, this is all besides the point if the vampires are just FEEDING on humans, not KILLING them unnecessarily. Nothing wrong with just trying to eat. Everything wrong with disassociating and having the mentality of a canibal or murderer.