After the American was healed, Dr. Sadao was necessary to discover a viable solution to send him go. Yes, I think his final solution to the issue was the finest one that could have been found given the conditions. With adequate goods and provisions for his survival on the island, he intended to send him off to a neighbouring island. He asked him to join a Korean ship from there which would land him securely at his destination. In addition to saving the soldier's life, it also kept the doctor and his family from facing serious trouble if someone had reported the doctor's presence.