If he adds DRM, someone will crack it pretty easily. Other developers have put in "patron" only content and codes into games, and they got cracked too. This is a Renpy game, anyone can look into the code.
And I think he is forgetting something, if he does add DRM, it would piss a lot of people off. What's to stop those people from reporting this game to patreon? He is breaking TOS, pretty badly at that. Providing a fake game on the page, incest content, blackmail content, shota content. He'd get banned.
This is a classic "don't bite the hand that feeds you" situation LP wades into if he adds DRM. He needs to get over piracy. Runey, who is a much bigger developer than LP is, is an active and very friendly user here. Other developers who also dislike piracy post here too and are friendly. Meanwhile, LP keeps shooting himself in the foot and being antagonistic towards his main source of fans. People downloading the game on this site.