The article was very unclear, perhaps intentionally so.
I don’t think anybody objects to your taking potatoes out of the ground and feeding them the pigs, as I think the law refers to table scraps only. If the article explained why the family had so many table scraps available, it sure didn’t say.
I used to live in Idaho, where there were massive potato farms. A guy established a feedlot for cattle north of town, and fed them pretty much on potatoes that had spoiled in storage. You would not believe the odor from bovine excrement produced from rotten potatoes. I wonder if there is something similar going on here.