I actually was kind of thrown off my the spirit portal line in this episode. In the premiere they talked about the Northern Lights like they were a normal thing to see in the sky, which to me would mean that the Northern Spirit Portal was already open. Unless I missed a line, nobody said anything about the Northern Lights being gone or that portal being closed. I actually thought that was kind of the point of the first two episodes. Maybe he just wants to send Korra up to the North Pole to get her out of the way while he takes over the South. One thing I will say, though, is that I appreciate the difference between this series and A:TLA, where the peaceful Waterbenders (and the rest of the world) were constantly being oppressed by the Fire Nation. It's interesting seeing the Water Nation being the aggressors this time.