Not to get too pedantic but I think an important distinction - Steam doesn't release games... it's just a storefront/platform and has nothing to do with developing or releasing games.
That said of course - they shouldn't be listing it/selling it, and it shouldn't be legal for it to exist. Unfortunately though, while this seems to be hitting mainstream, this is not the first game of this sort, the most famous being "RapeLay" way back in 2006.
https://en.wikipedia.org/wiki/RapeLay