This forum never fails to entertain me. Really? Folks are uptight about surface rust on the seat frames? Why the hell is anyone looking under there anyway? NO manufacturer paints the frames. At best, they have whatever rust preventative remains on the sheet metal after manufacturing.
What you see in the pics does not have any ill effect on the seats. And it never will. Unless the car is full of water, what you see there will never change. People need to stop looking for trouble...