The thing is, this guy can't change. He is doing exactly what he has been taught.
Your horse absolutely should be trimmed and balanced medial to lateral according to the bone. I don't care what the exterior job looks like and the current traditional protocols for this are wrong. We ALL know imbalance causes long term issues. The radiographs tell the truth here. Her leg is what it is and this intentional imbalancing to make the foot "look" straighter is not correct.