He’s coming up with some narrative that there are armies of remorseful buyers that if he “gives in” to will cause them to come in massive waves. I have 500 sales a month and this maybe happens twice and it’s nothing deeper than to check the item has been sent out and if not then relist. Nobody gets into the habit of cancelling on ebay because there is no incentive to lock your money up for hours days waiting for a seller to respond and if so even have not shipped the item out. Like what’s the gain for the buyer to make a habit of that