Are you saying that if you were him, you would fuck them hard after all this teasing? or do you expect him to have a dominant gig where he overcomes his sister’s pestering? Is it that easy?
What's the actual prevalence of incest? Let's make an uneducated guess and say it's pretty small... and when it is it's usually by people with deep psychological issues. So, no matter what, no AVN with incest is going to be realistic in any way, can we agree on that?
So, that being said, the whiny nature of the guy is just annoying to me and because the whole scenario is not reflective of reality it's just unnecessary. You don't see it that way, that's more than fine, you certainly don't need me to validate your opinion, and vice versa.
Myself, I tend to not look to AVNs for deep psychological analyses, though I have been surprised once or twice... this work isn't one of those surprises.
And, to make it clear, I'm no alpha male promoting 20yo incel, I'm 40+, married and markedly left-wing. The whole alpha male, Jordan Peterson schtick is nauseating. That doesn't mean however a male character has to go into an existential crisis every time he loses a sock or gets soap in his eyes or burst into tears when he sees a puppy.
Am I advocating making the character jump the sister or mother at the next opportunity... no, but a natural hesitation can be handled better. Is expressing/ruminating over guilt at feeling like he does an issue? Not at all, if done well (or even mediocrely) it can deepen the story. But, frankly, in my opinion it's overboard and descends from understandable to just plain whiny... he's just a poorly written annoying character. And again, for me.