From those positions in the video, if he transitioned to North South there's a high likelihood that he wouldn't be able to control the head or isolate one arm or a neck. That can be a decent solution to folks that are great at locking up NS chokes, RAT's, spinning armbars, etc but riding out their arms getting tired and waiting to act on their transition while keeping a more dominant side control was a great choice. Overall, very technical match and good job, Brian!