Darnell is the antagonist. If he's not a shit bag that is going to bumfuck your sister, your mum and all the girls you are after, then he's no longer the antagonist anymore.
I don't get it. The entire point of having an antagonist is to get you invested in the story and to eventually feel the sense of victory over them when you beat them. I think it's fine. Hell I think it's better than fine, I think it's great. I fucking hate Darnell and I think it will be awesome to fuck his sister in front of him and I think his presence in the game's narrative adds some much needed drama to a VN that is otherwise just a complete power trip.
If anything I think they need to give the reader more reasons to hate Darnell. It'll make gong after him just that much sweeter.
My biggest complaint about the VN other than obvious bugs is the lack of a branching narrative and obvious continuity errors in the dialogs that have been there for literally years at this point.