You've got it reversed, it's Patreon that doesn't allow underage and/or loli or incest, that's one of the reasons SubscribeStar was formed. Also, it would not end with LiL, going after LiL in that way would be going after other games as well, potentially ones played by the one to go after LiL. It really isn't worth the collateral damage.
As another user posted, it is against the tos.
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The issue with most games of this genre is that they operate in a form of gray area. Be it because of the way they make the CGs, or because of the kind of content. But yes, it isn't worth the collateral damage. That is the real reason that most of these devs make their games free, not because of goodness of their hearts. I don't think they can legally sell these games. The people in patreon/Subscribestar aren't paying for the game, they are only supporting its creator. I'm not even sure if keeping these care packages behind a paywall would be legal. At least, that is how I understand it, and I'm not a lawyer, so take a grain of salt here.
The best way to keep having these games (and keep receiving money from them) is to not stir shit. I don't think Subscribestar wants to enforce these rules now, but everyone has to keep in mind that they might eventually.
Btw, I get why he is mad. Making games is hard work, and everyone wants to be paid when they work. What some devs don't get is that piracy is a good problem to have. It means, before anything, that people do want to play said game. And it will only happens when a bunch of people are playing a game. Things are bad when you don't have enough supporters to worry about leaked content.