They could probably blend within the fender itself without involving other panels. If they blend into the door, then they have to deal with everything involved with painting the door. Like removing the window molding, the side mirror, the door handle, masking the entire car. Thats a lot of extra labor considering the paint on the door is perfect already.
I don't see why they cant sand out the scratches and make it smooth. Spray a little primer on the area of the scratches. Sand that smooth. Then spray the color over the primer and a little past to do the blending. Depending on where the scratches are, they could blend within the fender. Then re clear the whole fender. Since the fender would be off the car, you wont have to worry about over spray or any other damage.
While I'm not a professional painter, I have did some pretty good paintwork with a rattle can on cars that I've fixed up in the past. I try to not repaint anymore then I have too. My car has had single panels repainted (by a professional) with no blending. While the match may not be 100% (it's very close) I'd much rather have the paintwork localized to the one panel with damage, then extended to panels with good paint. I could be wrong, but I don't think blending into the door is necessary. Maybe what he could do and go with my idea, and if it doesn't turn out, then blend into the door, hood, A piller and whatever else they need to do. Might as well have the whole car repainted.
I don't see why they cant sand out the scratches and make it smooth. Spray a little primer on the area of the scratches. Sand that smooth. Then spray the color over the primer and a little past to do the blending. Depending on where the scratches are, they could blend within the fender. Then re clear the whole fender. Since the fender would be off the car, you wont have to worry about over spray or any other damage.
While I'm not a professional painter, I have did some pretty good paintwork with a rattle can on cars that I've fixed up in the past. I try to not repaint anymore then I have too. My car has had single panels repainted (by a professional) with no blending. While the match may not be 100% (it's very close) I'd much rather have the paintwork localized to the one panel with damage, then extended to panels with good paint. I could be wrong, but I don't think blending into the door is necessary. Maybe what he could do and go with my idea, and if it doesn't turn out, then blend into the door, hood, A piller and whatever else they need to do. Might as well have the whole car repainted.