You said his account is associated with porn and you haven't described him as the most resilient. I can see a perceived privacy issue even if he wasn't weak-willed. It also sounds like there's some lingering level of hostility toward you, so even if he didn't feel like his privacy was invaded he may still use that as an excuse to one-up you.
I'm not sure what you want. You said in your post you think you can wash your hands of this person, and I think for your own well-being you're probably right. So "us" reaching out to him comes across as a contradiction... we're not your personal army, brother, and posters here speaking to him because you want them to is not washing your hands. I think I understand why you sympathise with him, but he comes across as a leftist in a tailspin still clutching at "owning the chuds." Unfortunately, it sounds like he thinks you're one of them.
Edit: I also want to add that any Reddit posts that would bring up mending old relationships out of the blue would come across as extremely transparent. I think a lot of people would be pretty suspicious of the timing. I feel for you, man.
I agree, which is why I brought up Bari Weiss doing that.