I was going to say that initially I also couldn't see the difference in painting a stock model, and painting a previously converted model. Surely both are being painted from scratch. But then when I actually thought about it ... the converted model could possibly add a flavour of it's own to the finished piece, just by the alterations/pose etc. which try as we might to ignore, the brain/eyes would (subconsciously) see. So now I see the logic behind not allowing a previously converted figure being allowed.