Well when he gets bored with it again he'll no doubt think of you get a new bike and give you the old one for free.

with scrap metal prices up you'll no doubt have alot of competition for people ridin around in trucks just picking up scrap, I tossed a broken weedwacker in the alley and 2 hours later it was gone, try to get to know a few and offer them 2x scrap value, which is hardly anything for a bike frame. also just head to whatever scrap dealer and ask them to keep bikes for a few days and look them over. I've found people tend to gravitate more toward shiny new aluminum junk bikes rather than the distressed looking nice (lighter) older bikes that can look almost new again with a little effort.

good luck