Why is it unreasonable? The MC already killed Javier without hesitation or remorse.
First, it's Nicke's story, and players shouldn't demand any accommodation. If you really hate option you can't kill a girl whom you you were boning day ago, maybe this isn't story for you. Personally, when I find thing I cant swallow in the movie, book, novel, game whatever... I drop it. No point in continuing something I dislike that much.
Second, she really didn't deserve cold blooded murder, and it makes MC no different than people he fights against.
The MC already killed Javier without hesitation or remorse.
Not sure why do you pull Javier so much. It's not such strong argument as you think.
First, he was innocent for MC's mother's death. He was later involved in covering it up. Why would wrongful killing of him, somehow justify killing of Catalina?
Second, by the story he certainly did other crimes. MC even states he did, I paraphrase, 100 things to deserve hell. By all we know about Catalina, she didn't reach that level of evil.
So, in end what's so reasonable about Black Orchid's and your demand for murder of Catalina?