Yes, you've got it right. Here are two pix of my C50 seat. Notice on the img_0002.jpg that there's an inclined support under the seat at the front end that comes in contact with the metal piece that is bolted on the fender.
If you turn the metal piece, the extended part would go under the rider seat and there wouldn't be any support for the passenger seat. I'm not even sure if one could bolt the metal piece pointing forward end.