Why should the script kill King Roan. On the first place, the king of all powerful Ice Nation must not have been wandering alone in wilderness where he encounters Clarke, and is eventually shot in the arm and then captured. There had to have a fleet of bodyguards with him to prevent these events from happening. It was different from the first time he had captured Clarke, at that time he was banished prince, so had to be alone in wilderness. Now, it seems no one in the entire Ice Nation came to know about him getting captured, as there were absolutely no attempt to rescue him. And then, he goes to the city and is so summarily killed, absolutely for no reason, it is demeaning for the concept of Kings and Nations. ELIE didn't get anything from killing King Roan, so she should not have got him killed. An AI is not supposed to get someone killed for no reason.
Jasper says that Connor "choked on plastic, thanks to Murphy." Murphy actually smothered Connor with a rag in I Am Become Death (2014).