In this dungeon, there are specific spaces that are considered outdoors. Do flying creatures within these spaces have the soar ability?
And yes, we know that NORMALLY, there is no soaring in dungeons. However, since this dungeon includes pieces from Tomb of Ice, which came out after RTL, it is possible that the intent was to have a hybrid dungeon/outdoor configuration.
Even in the description of the dungeon, it specifically mentions the following:
"...ahead you see sunlight, and hear birdsong ! As you gape up at the impossibly shear walls of this hidden valley ..."
So, you can see that by the description, it is possible to believe you are outside, even though you can never soar in a dungeon.
Given all of the above, how do you rule?