They fixed it!!
The guy at the desk when I picked it up says they waited for the best tech to come in and do it and that he thought it wasn't too badly damaged. Not sure if I overreacted, or if the steel is just very good and the tech guy very skilled, or if I will suffer later if it fails at some point. I don't ride in a style that would put me at risk of serious injury if my back wheel locks up.
They put the old derailler back on too, which surprised me as the first guy who looked at it said that would have to go. The repair guy wasn't there and the desk guy didn't know it they had replaced any parts, like the jockey arm of the derailler. It looks perfectly lined up and worked fine on a 10 km/6 mile ride home, and the steel of the dropout looks completely normal with just some light tool marks on the paint to suggest it has been deformed and reset. Mind you I didn't remove the quick release for a more thorough look
I don't know if DMF was being serious or sarcastic in suggesting a dork disk, but I am tempted to go back and get one. It was an unlikely accident in the first place, and will probably never happen again, but if it did I wouldn't want to bend the steel back into alignment a second time, and would feel pretty stupid!
Thanks for all your support!