Setting aside the question of whether censored words should be censored if they are content displayed in a onebox, I’m thinking it might be a bug that there’s a difference between what is shown in the preview panel while composing a topic, and what then displays once the topic is posted.
I was a bit surprised to see my phone numbers displayed after the preview led me to believe they’d be hidden.
We merged a fix to make the preview and actual post consistent. I am investigating the possibility of censoring Onebox contents, but as Sam stated before, that is a much more trickier problem.