I'd untension all of the spokes and see if the rim goes flat by itself. It may not be as bad as it looks and you might be able to flex it back flat. If nothing else, it is a great learning opportunity. I am no expert at truing, but I would love to take a crack at that one.
I think that the LBS just didn't want to have to mess with it. Especially if they have a lot of other work piled up that can be finished with less effort. just my opinion though.