My take on the story was that Nidhogg came swooping down and Thordan leaped up to intercept.

I think its almost without question there is more to the tale. However I doubt its going to be clear cut on either side. While the Ishgardian founder may have been guilty of wrongs, Nidhogg and the Dravanians have not discriminate in their war, slaughtering the weak as ruthlessly as they have the strong. From my experience of FF14, I expect we will find issue with both sides. Its also possible both sides are getting played by Ascians.

Also there is the comment in 2.5 that there are two Wyrmlords in Eorzea. That could suggest that the Dravanian leadership could have it's own factions. That could create an interesting politic dynamic among the Dravanians.