I think the point was that the cho clan would have used any means necessary to acquire the throne even if he had…
Since he is dead to the world, with no known children or wife at the time of his supposed death. Succession struggle is null. Think of his fisherman uncle who says, "in the end, we all bleed red blood". In the end, him being a "good ruler" chose the best possible path (at that particular moment) for the people.
Man this series was gr8 but the fact that a phoney King came to rule is annoying for me. How could Lee Chang turn…
I think the point was that the cho clan would have used any means necessary to acquire the throne even if he had killed the child. It was the best possible move at that time for the people who needed rest from the war and the plague.