The author used this word because he is writing for the narrator, the grandpa, who has a negative feeling towards how his daughters take care of his grandchildren. He expresses through this word that the narrator feels that Glendine, the mother, doesnt really care about her child and just lets him stay up watching tv. Since crumpled has somewhat of a negative connotation, this is a good word to be used to describe the narrators feelings toward how the mother raises her child. Another word in the passage is shag. Once again this word has a negative connotation. The author could have used the word dirty but instead he used shag.
Shag is defined as a carpet or rug with a long rough pile. The author uses this word to describe the rug, to once again symbolize how the mother raises her child. She lets him lay there all night on a shag rug and watch tv all night. When one hears the word shag they think of excessively long hair or dirty. Some people described the hippies as having shaggy hair. So to describe this rug as shag describes it as being dirty and long and rough. If you were to describe the rug as soft or cozy or plush, it would have a warm feeling meaning the mother raises her child well and there is a positive connotation towards her.