https://www.pcgamer.com/valve-says-it-will-no-longer-police-whats-on-steam-unless-its-illegal-or-trolling/

In an official blog post today, Valve's Erik Johnson clarified and expanded on the company's reasoning when it comes to what games are and aren't allowed on Steam. In short, starting soon, Valve will allow 'everything' to be published on the Steam store, so long as it isn't illegal or "straight-up trolling." Johnson doesn't explain what counts as trolling, although Valve did use the word 'troll' to describe the developer of the school shooting simulator which it recently removed from Steam.

Johnson says that Valve's decisions have nothing to do with pressure from payment processors, something which 'Cut Content Police' creator Marusame speculated was the case in a recent PC Gamer feature on the tenuous status of games with sexual content on Steam. (We asked Valve for comment before and when that feature was published, and this seems to be it.) Johnson also says that, contrary to popular belief, Valve does not automate everything, and real people do review "the contents of every controversial title" submitted through Steam Direct.