It might be repairable I have never had to do so or been inside one but maybe some tech kid could figure it out with some time and money however if the shifter is a newer shifter you might reach out to Shimano and see what they say. Dura-Ace components have a 2 year warranty and while this was a crash and generally may not qualify but is worth at least asking.
I would kind of agree with
soyabean to a degree you should trust your mechanic as that would be a pretty high level repair and most shops probably wouldn't get involved.