There is kind of a policy but it's when people notice a game breaking issue like that, like there was a game that had an unbeatable first level and the dev just said it was really hard but there was an answer, then inspecting the files people proved him wrong and steam allowed refunds regardless of playtime and I believe the game was pulled. Most times however when a game breaking bug is found devs either release a patch or if they're too lazy to do that then they pull the game from sale because they don't want the bad reputation from people buying it and it not working, hence why you get some developers pulling older games that dont work on newer machines at all these days.
So the key things to take from this is that Wu is too lazy to patch and fix the bug, doesn't care about her reputation enough to pull the broken game, and nobody has really bought it so there's not enough of an outcry for steam to notice and pull the game.
I think bigger than the game being broken is how the special edition dlc advertises trading cards but there aren't trading cards or backgrounds or emoticons, even though Wu posted a picture on twitter showing her submitting them to steam and having done work on them. Meaning Wu didn't press a check box or some shit to make them active. It's not a big thing but developers do get money from trading card sales on the steam market, so there's another example of Wu not caring about getting any money from this game.