>>15872I think this is connected with the moving islands. It's a common thing in mythologies to have giant whales mistaken for islands, and this is combined with the other recurring trope about floating islands to produce the logical result of air whales.
A more scifi take on this would be that whales are actually a rather good design for a floating ship, because of the aerodynamics and the lack of need of wings because of the anti-gravity device or whatever.
However, it'd be really interesting if there is indeed something more to it. I wish I had friends interested in specifically the mythological aspect of cultural studies.