I'm not sure there's any supposed here. Strong magic such as storms of magic weakens reality so spirits can act more freely, but that doesn't meant ghosts are aligned with any of the winds that forms a storm of magic, or with Dhar.
I was talking about it from a college paradigm and under that paradigm everything in the world material or physical is aligned with one wind or another.
Toothpick: Well if it is made of wood that is a remnant of Ghyan and if it is metal that's Chamnon
Oil Lantern: Well the body is metal, so Gold Wind again, the flame is Red and the light is White
Cute Hamster called Mister Snuggles: Well he is a beast so that is Ghur, but he does have a tendency to cause warm fuzzy feelings, that is the Red wind again

So where in that paradigm do ghosts fit to see if any of the colleges can steal their trick of speaking to souls, are they a natural manifestation of endings? I would maintain that they are not since ghosts are defined by the fact that they linger... so if they go against the natural flow of one of the winds what does that leave but Dhar?