What happens when you have 2 AI on your team? 
Had a game the other day where a player dropped about half way through but we kept playing because anything was better than how that guy was doing. We were struggling to match the creeps of the other team and he went and proudly announced he bought a godplate and was now "invincible", then he proceded to die a couple of times. I don't care if the other team goes after the AI, I usually try to baby sit it as much as possible and it usually works out ok.
When the other team has the AI I try to kill it whenever it comes near. No way of knowing if the other team requesting it not to be killed wouldn't do the same if they were fighting an AI.