Because he wasnt accepting people offers to pick it up because the price wasnt high enough. He posted it for $500 and when you called he would just start a bidding war with everyone. Now for whatever reason he couldnt sell it so its back on the market. Either the car is a complete POS and whomever had the ishest bid turned it down when they saw it in person, or he kept trying to upsell it so much that no one ended up getting it.
Those kind of people piss me off. Post a price and stick to it. Dont be a fucking tool about it.