It may help a little. But during the cycling process I doubt you would notice anything at all. In the most part he is right though, the bacteria we rely on is arobic(oxygen loving). It NEEDS oxygen. Your basic filter and water movement supply plenty, your fish will suffocate before your bacteria will. When provided with a oxygen rich environment the bacteria can be much denser than in a low oxygen environment. Some filters take advantage of this. For example a wet/dry filter or trickle filter will support a much larger amount of bacteria(and in turn a larger bioload) than a HOB or canister. They do this by keeping the media exposed to the air and in different manners, trickling or dripping water through the media. That way the bacteria has all the oxygen it wants and the media doesn't dry out either.
A cheaper and more common example is the biowheel. As it spins it dunks the little spoke/riffle parts in the water and spins them through the air.
My only bone to pick with these filters is that if the power goes out or for some reason the flow stops, you run a much high risk of the media being dryed out. The biowheel it not as bad, but I dislike HOB filters in general.