Hard to say. In the past this would probably have been permitted but they seem to be clamping down recently and requesting people to take more direct routings. However I would certainly think it is a legal routing in the general airline world but that doesn't always translate to what the ICC tells you.

To give you some hope though I had a similar routing ticketed a few months ago routing FCO-BKK-PVG-NRT on TG/NH and I got away with that. Might want to try another agent. It might also be an easier sell if you start the journey at a gateway with a direct flight to BKK and not ICN.