If he exchanged words like mother and sister for something else, would not that be possible? Although he left the game poorly written, he would patch for incest to come back, posting on some website.
He probably could, if he changed it to a roommate situation, where no one was related to anyone else. Step relationships aren't allowed. But that would involve a lot of work to re-write it and still have it make sense. But there's two problems with that approach.
1) At least at the moment, DS would rather work on Glamour.
2) There's no guarantee that Patreon won't crack down on people changing incest games to games about roommates, and then patches mysteriously appearing on the internet. Except it might not just be warnings. It could be bans at that point, which scares pretty much any developer, because Patreon is the place to be.
And honestly, I don't know much life Big Brother has in it. I suspect that it would still be more profitable than Glamour, but people were getting frustrated with the pacing. Update .13 was a good one, but at the same time, DS can't give us updates like that all of the time, because Ann was what people had been waiting for for so long. For me personally, I'd like to see one more update featuring Lisa and the taking of her virginity, and after that my interest would drop drastically.