Rabulias
the Incomparably Shrewd and Clever
I would say they are no longer prone.
Consider the disadvantage on ranged attacks vs prone targets. If a creature is lifted into the air in a horizontal position, their exposed target area to creatures below them is roughly the same as if they were standing on the ground. Is Superman prone when he flies through the air? I think a flying humanoid in an upright position would actually present a smaller target profile to creatures below them. By the same token, a flying creature above a prone humanoid target should have no disadvantage on ranged attacks.
One could do 3D spatial positioning rules, but it gets very complex very quickly for very little benefit, IMO. Far easier to just say in this case the various pro and con factors cancel out.
Consider the disadvantage on ranged attacks vs prone targets. If a creature is lifted into the air in a horizontal position, their exposed target area to creatures below them is roughly the same as if they were standing on the ground. Is Superman prone when he flies through the air? I think a flying humanoid in an upright position would actually present a smaller target profile to creatures below them. By the same token, a flying creature above a prone humanoid target should have no disadvantage on ranged attacks.
One could do 3D spatial positioning rules, but it gets very complex very quickly for very little benefit, IMO. Far easier to just say in this case the various pro and con factors cancel out.