Not sure that I'm really understanding what the issue is but lets have a go.
You are the seller. You file an unpaid item dispute for a non-paying bidder. When enough time has passed you close the dispute to recoup you final value fees (not your insertion fees - those are gone forever although you may be able to relist the item and get the insertion fees credited if it sells the second time around).
Now the non-paying bidder has placed a neg against you (justified or not). If the NPB did not participate in the dispute resolution process, the neg against you will be removed. If the NPB responded to the dispute you are, unfortunately, stuck with the neg.
Or maybe not. I would next pull the NPB's contact info and make certain that he/she has a working telephone number registered with eBay. If not, you can approach eBay to remove the neg because the buyer has inaccurate contact info on file with them. It is one of the legitimate reasons for which eBay will remove feedback.
If his contact info is accurate, all is not lost. From his comment there appear to be some bad feelings but it is still worth a shot to see if he/she will agree to mutual removal of feedback. The neg will be removed from your scorecard but the comment will remain.
Last option is to pony up some cash and see if you can get SquareTrade to resolve the issues between you. Personally, I don't like to see money sent to SquareTrade but, if you want the neg removed bad enough, it may be worth it to you. It assumes that the NPB will also want to work with SquareTrade.
Good luck,
Bill
treasure-pot
Bill
