I didn't reply to the original post as I presumed my opinion might not have much weight me being a shop owner.
Having sold brake service for nearly thirty years, this issue is probably the least mistake I have seen. I doubt that it has happened in our shop in at least ten years as the bleeder technique solves the problem.
As stated above the only damage is the stain on the hood pad. It might be beneficial to rinse the pad with water. I would spray it with a windex bottle and then flood the area it drains to. A hair dyier should dry it out. Leaving the brake fluid in the hood pad will probably destroy the painted undersurface of the hood (above the pad).
I would catagorize this as a minor non-safety related indescretion. I think the hood pad issue can be dealt with without replacement but the shop probably would be willing to replace it if that brought satisfaction. The issue to me is minor carelessness or working under too much time pressure. My advise is accept the incident as an accident. let them bring you satisfaction and if they do decent otherwise keep using them. If this works out you have the basis for a strong relationship. I believe having a strong relationship with your technician or shop brings great value.
Bosch Master, ASE Master, L1
33 years MB technician