In legal terms, you do not have to intentionally break a law in order to break it. If you seduce a woman and she claims to be 20 when she's in reality 14, you've still broken the law. Severely. Even if it was accidental.
Why does that matter? You reposted something that has a connection to illegal content, which is against site rules. Period. It doesn't matter if someone else posted it, you did too, and because you did, you broke site rules.
If you can't control your behavior, you shouldn't interact with people. I am autistic myself, and I have severe social anxiety and depression. That doesn't make me exempt from social activities, arguments, or uncomfortable situations. I still have to do things I don't want to do, and my mom still yells at me when I don't do the dishes, even though it freaks me the hell out. But, I didn't do the dishes, so I'm going to be held accountable.
You posted in a public forum. Everyone is entitled to the right to respond to your post, unless the site administrators decide otherwise. You came into our space and did things, we can say you're full of crap.
Again, that doesn't matter. Intentional or not, you posted it and thus broke the rules. In the US criminal justice system, you would be arrested and charged with violation of 18 U.S.C. § 2252, unwillful distribution of child abuse content.
OCD is controllable. It can be as simple as Exposure Therapy (which would be exposing you to what would normally cause you to become impulsed and then NOT FOLLOWING THE IMPULSE).
Source:
NHS