Ai can combine two things. It can train on completely normal pictures of children, and it can train on completely normal adult porn, and then it can put those together.
This is the same reason it can do something like Godzilla with Sailor Moon's hair, not because it trained on images of Godzilla with Sailor Moon's hair, but because it can combine those two separate things.
That is absolutely not a free feature on Steam. Some publishers like Paradox leave old versions as 'beta' branches to allow us to reinstall them, but Steam as a whole is very against you playing anything but the latest version.
You cannot instruct Steam to not update a game. When you launch a game, Steam will update regardless, unless you have gone offline, or you launch it in a way that bypasses the Steam client. If you ever forget to go offline before launching a game, Steam will forcibly update it