Floorplan negotations are never easy. Hell I've seen people go to war over what side of the room a theoretical coffee pot would be placed on.
I would only imagine in a $1 billion situation it would be the ultimate power struggle. It's not that they couldn't install the retractable seating, maybe it's just that they don't want to and why should they if the team sharing the space is only going to use it part time?
Vikings have played in a bad stadium for a long time, they were going to play hard ball on this out of principle.