Buyers report on satisfaction when the article is received, thereby also acknowledging receipt. Disreputable sellers can often not report feedback until after a buyer reports. This goes un-noticed with positive transaction typically, unless a buyer has a complaint. Even after escalating the issue to management, Safe Harbor would not consider this or any other adjustment to the process to prevent this form feedback extortion. Most likely, they have too much to do just keeping firearms, submarines, refugee rafts and body parts off the listings.
Sellers can arbitrarily refuse to complete a transaction with a buyer.
If the buyer has any negative feedback, is a new bidder, or perhaps if they have blue eyes - the seller can contrive a reason to move on to the next bidder on the list. There is no equivalent right of a buyer to back out of a completed auction, if say, communication after the auction closes concerns the buyer. The justification for this is that a reluctant buyer can waste the time of a seller. What about the buyer's time wasted following an auction, just be outbid at the last second. Or what is a buyer's time worth to chase down compensation from a seller, especially when a seller makes positive feedback a condition of any settlement.