Great fence sitting with abandon there. I agree.
Not so much fence sitting. More that I think that Moon with last episode and also Ophelia part in that with Nana has made a great setup for Nana to decide to make the step with MC if she is willing and ready. (it should be clear to her by now neither incest, age or close relationship is for MC any problem (more the opposite it seems
)nor does she have any reason to think MC cares less for her as those he does sleep with and she is also self aware that she is attracted to him both mentally and physically)
So if she resists for any reason that is stronger as any of the objections I mentioned above from her side, then to break that in future she will then need an even better reason why she would decide sexing with MC is fine and good and Moon will then need time to setup such a situation and likely before he can do that well, with also all other women needing their time, we will be talking chapter 5 at earliest.
I am not the writer though, so do not know whether Moon intends this to be the trigger to pull for Nana or has something else in mind for future. Just that would be likely quite a bit away then still.