I have three theories a to why the Jovian's helped Skolas escape from the Prison of Elders. 1) The Jovian's wanted to make profit off of us by using their equipment to fight against the "new" threat. They make an enemy for us to fight and we "buy" what they have. 2) The Jovian's wanted to screw with the Reef. They might have some bitterness towards the Awoken. 3) This one is a stretch but just think about it. What if the Jovian's freed Skolas to make an army in order to prepare for the Taken King. 4) What if the Jovian's did this as a way for the Awoken and the Tower to ally in order to prepare for the Taken King. A test so to speak. I'm open to discuss this.