I hadn't set sharing up since getting recently getting a Pro but I did remember a warning about stuff like this when signing up to the Share services. I've signed up on the new Pro now and this is the warning that you get before you accept the terms...
SEN said:
When you broadcast gameplay or upload a screenshot, video clip or other content to another service, a PlayStation Network activity will also be shared with other players based on your PlayStation Network privacy settings.
Also, content that you upload and your PlayStation Network online ID may be viewable together in [Live from PlayStation] depending on your privacy settings for the online services you use.
The issue with the OP is not that they've shared an image on Twitter but that they've broadcast that image to everybody in their friends list and the people they're following and, perhaps understandably, they've had complaints from a person or people who clearly didn't want to see it.
Maybe the ban extension was due to additional complaints about the shared image?
I know that some have suggested that it's the fault of the game for showing a, shock horror, vagina in a game but I don't think the band was about the OP playing a game with a vagina in it but making it public on people's screens when they turn their PS4s on. You can play films with whatever ratings and content you want on your PS4 without any worries about being banned for doing it but if you were to post images from it (You probably can't do the same with films) then it becomes your responsibility for sharing it openly on PSN.
Although I couldn't remember the specific wording of the warning I could certainly remember that I was warned about sharing from when I initially signed up to it. To me at least, if I chose to share an image publicly on a platform such as PSN with that warning then I would actually be expecting to be reported, at least once, and probably banned.
OP, I do hope that you sort it all out but, you know, be more careful in the future as you're inevitably going to piss off somebody by doing this.