Interesting idea, but it doesn't have to replace the suggested 3-button positive rating scale. You could have both.
The admin rating would be good for the reasons you suggest, but there should be some automatic reduction--say 1 point per week reduced automatically. That should serve the desired purpose, while offering a way to work one's way clear.
The 3-button positive post feedback seems like a great idea. It gives folks something to strive for. I like to see expectations raised, and this might just help do that.
All in all, having an admin negative and a poster positive feedback rating might be just the ticket.
Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.