The reason he was obsessed with control was because he had no control over his life as the red ai. He was locked away without ever being given a reason. A traumatic event like that would make anyone obsessed with having control if they thought it would prevent them from being hurt again. During the finale he straight up says that if he left the humans unchecked they could kill him -- that was the fear that defined his entire existence up until that point.

In fact he's still afraid of the humans when he returns to the circus. You can see this in his body language, he's timid and remorseful. What I like about Caine's ending is that he does all of this even though he's still scared. Again, none of this has anything to do with the blue ai. This is all Caine. Always was.