I don’t use ebay so I’m not sure how it works. Do you have to buy from someone to leave feedback? I remember seeing a website showcasing the work of a prankster who left “feedback” making jokes about people’s usernames on ebay (even though he had never dealt with them before). Perhaps this is another prankster like that. It’s a very cruel prank, if the person actually died.
Is it possible that the person may have “faked” their death to get out of paying or delivering goods? I know that is a horrible thing to suggest but there have been some cases where people have pretended to die online. Perhaps that is why this rude feedback was left?