If he really has no storyline planned out at all then this game will have way more problems than a kink being in there or not. He'll maybe make one or two updates and then give up.
I don't know if the dev has any story planned out but what's in the game so far doesn't seem to have any major plot lines.
At most the guy meets a girl who flirts with one guy then ends up getting MC off later. Playing devils advocate, NTR could quite easily be slipped into that part considering she was groping a guy when she met the MC first time.
Only 1 of the cousins have anything resembling plans and that involves getting him in shape.
One cousin was happy to see him but it doesn't seem to lead to anything, one cousin doesn't speak at all but acts like a queen, one is the usual angry angsty teen and the aunt tells him to help a friend of hers.
Nothing that leads to an actual storyline just a bunch of little events that, in all honesty, could be made to work with any kink at all, it's all open for anything.
Dev seems to be leaving it up for vote so with that kind of plan we never know what's going to happen which is why i've never seen it work. It's like devs think if they make it as interractive as possible they will bring in people willing to pay.