My Armand has a corner box filter in his 5g tank. He doesn't seem to mind the small single line of bubbles it gives off, but it does create a current. If you want aeration in his tank, get a small airstone and a weak pump and set it in a corner to try. If you set it right in the middle, he wont be able to catch a break from the current.
But aeration really isn't necessary because bettas have labyrinth organs. They come to the surface to breath air for more oxygen. Aeration just adds more oxygen to the water, but the betta will still "come up for air" every now and then. Basically, aeration for a betta, in my opinion, is just for aesthetics. Though, some bettas like the bubbles and current, they'll ride it up and down and side to side. But others may hate it.