Just a theory, but... What if the character who leaps is doing so extremely fast, which is why he can do it in one turn, ( remember the fly move in pokemon, hits on second turn), so what if due to the speed of descent it actually forces so much air away so fast it can push back nearby flyers? Or they pull back instinctively and suffer harm from exhaustion( no ap ) or disobeying whatever poxy-mumbo jumbo that summoned them and the avatar punishing them.
Wish it was restricted to only work with 2x2 units, its silly with small imps, frogs or garus coming and do seismic leaps. No this ability should be for Titans and their like
For the same reason a bomb affects low flying planes. Plane control would be affected enough make it veer off target and to keep it from engaging if the bomb was close enough.