Actually, I should have looked around a bit more before giving you that reference. There's also a place named Osuch in Poland which you can situate at
http://europe.mapquest.com/maps/map.adp?formtype=address&country=PL&addtohistory=&city=osuch and which I think is a much more plausible origin for the surname. Unless your friend would be happier with 'withered old man', of course.