Here is what I have done in the past. Leave the negative feedback, but first make sure you have copies of all of the e-mails he sent threatening negative feedback. Then tell him if he does leave negative feedback out of retaliation, which is not in the spirit of eBay, you will not only submit a formal request to have the negative feedback removed siting the e-mails as evidence, but asked he be removed from eBay for blackmail. I have done similar before and it works. Additionally, if you tell the guy this is what you are going to do, odds are he'll not leave negative feedback, if he does, turn him in. eBay does not seem to take this sort of manipulation lightly.
NoBonus
I sold an arcade machine on Ebay to a man two weeks ago. He had 198 100% good feedback points. We sent a couple of emails to each other talking about shipment, etc.
Then he sends me an email asking if I would let him pay on the 20th. He didn't want the balance to hit his balance before the end of the billing cycle. Since he had good feedback, I said sure.
A couple of days later he emails me back and says he has "buyer's remorse" and that his "wife had just lost her job"
I offered to hold the machine in storage for a couple of months. He came back and said he couldn't afford it now. I told him I'd take 1/2 and hold it for two months. Then he came back and said I should relist it.
I bent over backwards I thought. I told him I'd have to give him some negative feedback. I've had over 100 transactions and never, ever had to do that. Then he says he'd have to fire back with negative feedback.
He tells me that "it's part of ebay to relist items" He's had sellers "not part with their items" and he's had "buyers not pay" but he let them slide.
I told him it was simple, pay or negative. Non-paying bidders deserve negative feedback whatever the reason, and it underminds the feedback system. If there had been one negative feedback in his list for non-paying, I'd have made him pay on the terms of the auction. He doesn't seem to be a jerk, but he stiffed me on this one.
Should I let him slide, I think he may have ran into a problem. What do you guys think?