If he returns to the past before the events that led to Carthaginian victory and restores his original timeline by negating the assassinations and military upset that have led to the new alternative timeline, he would wipe out its billions of inhabitants when the course of human history reverts to his own.
If he returns to the past before the events that led to Carthaginian success and restores his original timeline by reversing the assassinations and military disruption that have created a new timeline, he would wipe out its billions of inhabitants as history reverts to his own course.