>That's just not true
Yes it is. I can forgive someone for being ignorant of the way the eBay feedback system works, but when you push that button, you are not just "notifying other perspective buyers of potential problems". It hasn't been that way for years. Not since eBay removed the ability to leave negative feedback for buyers, anyways.
If I were the seller in this case, rather than going to court, and negative feedback was still around, I'd have left them the same with something like "PITA buyer, - feedback for being off $1 in shipping. AVOID."
What you are actually doing when negging a seller is deciding "This seller made me so mad that I am going to cost them large amounts of reputation, raise their fees, restrict their ability to list, and possibly help drive them out of business". This is not an idle threat. Feedback is calculated over a 12 moth period, meaning if you only sell a couple things a year and get a single neg, you'll trip over all of the eBay restrictions and fee increases.
Now let's get some perspective here. The seller delivered the item, as described. There are no complaints about the item itself, so we can assume the buyer is happy with it.
Buyer's willing to mark the whole transaction as terrible over a freaking dollar?
There are some levels of shenanigans to which this is an appropriate response. $1 is not.
The more I think about it, the more I think there may be some merit to this case. If the seller offered to make the problem right and the buyer hit them anyways, given the effect that hit will have, is it possible they have a case?