If one has more retractions than bids, a surrogate bidder would be required that would allow you to retract his bid, protecting the surrogates ability to bid within the PWCC policy even if it is enforced.
I'm going to give this a little more thought, but my future may rest in a bid retraction enterprise which could be retained by eBay, PWCC and consignors everywhere.
I'll need a slogan though.