Its a shame that even after your art was modified to accommodate steam this still happened. I say to spite them you return to the even cuter style. If you are still looking to release on steam, removing all adult content is the only (still not completely safe) way. If there is a patch to restore content most people will still buy there as we are used to this dance already.
Viewing post in STRIP Battle Action Cards [Demo] comments
I agree to all of that and am planning to do just that. Cuter characters, safer Steam uploads. I'm not sure if I want to try offsite patch, it sounds too risky. I will at least make the safe version half price due to only having half the content. I'm unsure if I can post STRIP Cards on Steam again due to the metadata trackers, but I can at least ensure that my future games have safe alternative versions.