Are you taking the bid from someone with 13 posts seriously? Could be it is your alt account maybe, a friend or something along those lines?
I don't have any alt accounts in this forum and would never rally my own auction that way. It's up to the bidder if he sends the BTC or not, I just take the second best bid in case the winning big is a joke bid. Joke bidder will be added to a public list so they can't continue messing around too long.