The solution is simple. Slant the paper right-to-left. This allows the left hand to be positioned below the line of writing. The wrist is in a comfortable position, and the writer can sit with good posture. The hand does not get dragged through the fresh ink. Parents and teachers who see a child writing in the hook position can make a habit of gently repositioning the paper and the child's hand.
But please don't worry about it too much. Some lefties really feel more comfortable writing hooked, curled, leaning, or upside-down. That's okay!