I don't know why Adult Dev's keep on doing this and why people bother "talking about it" when it's all wrong all the time.
Steam is still a "Common Persons" store like it or not (and other than the Visual Novel fiasco's due to the School setting) it's always the same story.
T-Shirts for kids with "I'm my parents little cum-bubble" are sold (or "Spit Roast Whore Hot Sauce" being sold at a truck stop that everyone can see and buy), so is stuff like "Sex with Hitler".
Are they offensive? Very, but they are actively having dirty-tongue-in-cheek-fun with the product that can help skirt that line massively.
There is also a reason why many movies that are "problematic" from back in the day are still liked by many, because it's the total sum of it's part. It's only the movies that have nothing to offer that people will specifically ridicule for being so stupid and sleazy.
On the other hand, a game that doesn't pull any stops where they have a hardcore subject (ei: actively violating something, without a story, lore, etc). and that's the whole and ONLY premise are going to have a harder time being sold on it's premise. Quite a few games on Steam have some "extreme" hardcore adult content in them, but because it has some fat and meat on the bones, they can at least soften the blow on it (not to mention the writing).
Znel can do all the changes they like, the Sliders were simply the quickest and easiest scape-goat excuse they got. Why they decided "put safeguards" (seriously, doesn't anyone have any proof of this?) or only now to "limit them" after the damage is done (when they were already on 2-3 other places) is beyond me.
Sometimes it's better to have a smaller but more lucrative base without rocking the boat, rather then a larger boat where you need to keep on throwing out content to meet the quota.
Personal Opinion that doesn't matter: This is a sign the Developer isn't financially happy and wanted to get more money by accessing a larger potential selling pool.
I get it, but maybe they should make an actual game or massively update this one? I mean their updates are nowhere close to what some (literally) free indie games get months apart, and those are original works. This game on the other hand also has a decent stack of asset use, so I don't know what they're doing with a good portion of the money if they're not re-investing it in the project.