Life's Payback has two distinct universes. If you chose to avoid the futa scene, Nina will never have the opportunity to use Lumeria's magic to give herself a penis.
I confirm that what is canon to the story is her being a cat girl with a pussy and nothing else. The futa content is just some extra stuff I wanted to implement after fapping to too many videos on Rule34.
Also let's not forget it's literally TWO animations out of 90+ and they're both avoidable. People tend to forget this when they call me a futa cuck on this thread.
I will soon implement an option allowing anyone to never hear about futa throughout the entire game.
As for the way the MC treats her, I agree that she shouldn't deserve this story plot, but as you saw, I'm gradually developing a narrative arc of redemption in her story, where he starts to be nicer to her.