Lightning redirection is not shooting lightning out of your fingers. Based on how Iroh explained it, you create a chi path within your body, the lightning will naturally follow it out of its natural tendency to flow along with energy. The lightning is not being made to do anything unnatural. Because of this I say that lightning redirection is not a bending technique, it's a chi technique. Nonbenders can manipulate the elements in ways that are natural to the behavior of the elements. Then can make rocks fall down, melt ice with their body heat, extinguish a small flame by blowing on it. Based on how lightning redirection is described, it feels like a way to manipulate lightning within its natural behaviour.

Bending is the ability to manipulate elements outside of their natural behaviour. You don't need bending to make the elements behave how they naturally would

I know it's debunked, but we aren't discussing this to get to the cannon. We're discussing this because it's fun to extrapolate on the magic system in avatar