Its not so much air resistance that causes it, as it is bernoulli's principle in play. The boomerang is essentially a 3 winged air-foil (2 in the traditional sense), with the angle of attack set to create an equal thrust force in opposite directions, resulting in a torque (which also causes it to elipse as it does).

And I dont think youd find a sane man alive to take that bet. No fluid, means no pressure differential, means no net force in any one direction....which means no elipse.