Ah, but without liquid in the flask it's an apples to oranges comparison, running a stir bar in air will move a lot more air than a vortex in a liquid.
I'm no aero/fluid dynamics expert, but I don't see the vortex in liquid creating much of a vortex in the air. While the air vortex may create some motion, I'm doubting it would do much to aerate the wort.