I commented on the text in the image, which made it sound like someone murdered their rapist after a court let him go.

That is what happened.

And I will disagree with that kind of vigilante justice on principle.

On that we can agree. But your principles, and actual realistic expectations do not agree on this. I understand this and you don't seem to.

It might be understandable, I might not even be sad, but it's not something a civilized society can tolerate.

There you go, circling back again. So we can tolerate the rapist going free, but not the woman he raped making up for society having already failed to stop him? This convo is over.