Exactly, and if someone else did get scammed by the same person it WOULD be better for them to post their proof in the same topic as someone else as the moderator who did the report would have two lots of pics of the scam in the same topic etc.
I think it should remain public, this way when your trading with some people, you will know if they where accused of scamming. And avoid them, if you think it neccisary.
Keep it public. I enjoy reading the RaS sections when I'm bored. Also, As many have said already, it helps people in the black market check and see if the person they are trading has been accused of scamming and what not.