Regarding incest, I don't think this has anything to do with the legal status of this kind of relations in the US or any other country. Mostly, this has to do with the fact it is a taboo —which is part of what makes it attractive— and negatively perceived by many people. If Patreon, like YouTube, for example, is trying to build a determined image for the site, one that makes it relatively safe for any person surfing the site, they need to make sure no potentially "shocking" content is visible that can scare off some potential visitors/users.
The fact that creators are resorting to just hiding the "controversial" content makes it explicit that this is, at the moment, merely a matter of public image. Highly hypocritical, if you ask me —on a side note, I find it extremely funny and paradoxical that there are so many millions of fans of Game of Thrones enjoying a story in which incest is pervasive and at the very core of the narrative—, but understandable from a commercial point of view.
The fact that creators are resorting to just hiding the "controversial" content makes it explicit that this is, at the moment, merely a matter of public image. Highly hypocritical, if you ask me —on a side note, I find it extremely funny and paradoxical that there are so many millions of fans of Game of Thrones enjoying a story in which incest is pervasive and at the very core of the narrative—, but understandable from a commercial point of view.