Seriously I just do not get this thing. Is incest bad? Yeah it can be but is this game doing any harm? No. It's not suddenly going to make me go rape my underage sister who I don't find remotely attractive, that's just not how it works.
If the intention is to prevent incest then it's just stupid. It's basically the same argument as video games causing violence.
I don't think this is the correct approach. Prevention of (what is conisdered) deviant behaviour has nothing to do with it in this particular case. We must first aknowledge that in most civilised countries incest, in any form or shape, is at least a taboo, if not even aginst the law. But so is polygamy, yet such fantasies pass with ease.
So it also has nothing to do with incest being harmful or not.
Would games where there's consensual sex between an adult and a child suddenly make you want to rape children? Probably not, yet that's not the point.
Would games where the main goal is to rape as many children as possible gonna make you want to kill children in real life and rape their corpses? Probably not, yet that's not the point.
Would tycoon games that reward you for cooking human body parts in order to create delicious meals suddenly transform you into a cannibal? Probably not, yet that's not the point.
Would games that contain incest make you want to rape your sister, like you just put it? Probably not, yet that's not the point.
Think of Patreon in terms of an art/painting gallery. You could find in there paintings that depict nature, abstract ones and even nudes. But the organizer is not to be blamed if he refuses to exhibit pornographic paintings. I mean it's not like the female (or even some male) visitors would feel the urge to masturbate right there, on the spot, when looking at a painting that depicts a big, black, juicy cock, but, once again, that ain't the point. He simply does not want to associate himself with that particular form of art.
As long as there are strong objections towards a particular subject within society, you'll have some form of censorship.
Saying that playing a game is less likely to transform a person to such an extent as for him/her to apply the acts depicted in that particular game is nothing short of a platitude and does not address the real issue.
I, for one, have no problem with any kind of fantasy/fetish as long as it is tagged accordingly and is not invasive. I tend to never revisit adult sites where straight pics/vids are mixed with gay ones, as a default for obvious reasons.
In the case of games with incestuous content, even if I am a bit frustrated with them becoming a standard rather than an exception, I do not feel for one second they are being imposed over me.