He's scanned the image, so he still essentially has a copy of it. While it isn't the same as not having the original copy, he shouldn't be afraid to proceed for fear of losing his work.
If he likes the way shaded pictures look and still doesn't have much experience with them, the best way to improve is to do just that.
That isn't the only reason I suggested it by the way, I think that it could look pretty good shaded.