He knows what he has. A pile of junk.. Also all that glimmers isn't gold. There are other yellowish metals used for corrosion protection.. Cadmium being one that pops to mind.
Even if it is gold plated. A little goes a LONG way as far as plating goes. You could likely smelt the whole pile and end up with less than $5 worth of gold.. If you were getting tons of this stuff for pennies a pound.. You could likely make money off it.. But you'd be making a lot more for the other elements.. zinc, nickel, aluminum, etc.. than you'd be getting for the gold.. Simply due to the quantities.