Why was the GFI being used in that location? What was it intended to protect?
Sometimes in dining rooms you will see them for buffet hot plates, griddles, coffee pots, food warmers and the like.
I assume that is what it was for. It was an upscale home so whoever built it assumed things like that might be used.
It was also not far from the kitchen so they just pulled the wire on around to the load side of the kitchen GFCO that protected all the outlets there.