If it’s salvageable in one complete piece but just thin, piece a new “top” and get new backing, then use the old quilt as the batting. It’ll make a nice soft utility quilt for him and you’ll have a clear conscience. You could use all scraps or maybe he has some old shirts you could cut up for the project—do straightline or easy meander—the whole project should be fun and done. I believe this was frequently done in our grandparents’ day. Let us know what you decide in either case.