Wrong, the patches wouldn't be allowed if Kagura Games or any user were to share them on Steam.
And the content of the patches are very much forbidden on Steam, from rape to shota/loli stuff.
If the patch was allowed, they would just add it on Steam as DLC. What Kagura Games are doing is a workaround to the rules.
Steam rules aren't what you should give consideration to so much. They aren't consistent with it at all and will pick and choose what to allow or ban. Even if your game 100% abides by Steam rules, they can still ban it for any vague reason if enough people complain about it. I've also seen games that got rejected by Steam later got approved just by a name change which itself contains rape while the patch provided outside is to decensor the genitalia.