Isn't that like saying if a being is omnipotent, that it should be able to create a rock that is not a rock, and since that is impossible, an omnipotent being is impossible?
Also, it strikes me as a bit of an assumption to think we could make broad sweeping claims as to what an omnipotent being could and could not do, given our little brains.
If this guy takes it any farther, he best be extra careful at zebra crossings.