This is a very good point that someone made too 🙂
If Zelena was exiled at some point she could have been running “things” from “Kansas.” She could’ve been controlling August’s actions. By making sure Emma gets to Storybrooke, it destroys Regina’s happiness. We know Zelena wants to ruin Regina, making sure her nemesis makes it to Storybrooke to break the curse would be in Zelena’s plan.