There are quite a few games out there which techncially violate patreon's TOS, but until now they don't really seem to be that hard on the whole stepcest topic and even smaller incest games do get away with it. I'd guess patreon rather takes the money and doesn't want to bother. SS on the other hand is the #1 game in their NSFW department, so we can be sure they'll check and DC certainly has enough "haters" who would report stuff to get him banned, too.
In the end he made it clear several times that he wants to be on the safe side in basically every way. That's why we don't have incest in any way, that's why there isn't an official patch, that's why we don't have a really flat chested schoolgirl, even though many people wanted someone who is smaller than Missy, that's why there are no real disney references, etc.