I understand that, and I also understand how Banjorune feels. I don't think "Patreon's policies are unavoidable so the customers hurt by the consequences of said policies are in the wrong" is the correct resolution at all.
There doesn't even have to be a solution to this problem - if it's unavoidable that Patreon is just harming everyone, then you simply blame Patreon and the developer has his hands clean (and so does that user that complained). However, there are other ways out - for example, the game could give the user a free choice of role, and only provide the incest content if the name of a familial relation (i.e. sister, brother, mother, father, cousin) is given as the character's role. This censors the incest content even harder, but still makes it available for those who want it.