The exact partiuclars of this case have not been shared, as such its very difficult to establish a legal basis.
However if one indulges in a little supposition -
From what I can gather, the purchaser left negative feed back, however instead of just reflecting the transaction in the comments, he (the purchaser) stated a reply likening the seller to "a used car sales man"
however theres no information on if this has gone to the next stage of court, its likely if the persuer cannot prove a loss to his business this will be laughed out the court and he (the persuer) will lose a small sum of cash in costs.
Its interesting that the persuer went after the buyer as opposed to eBay, infact if he has not sent a "take it down letter" this case will be laughed out of the courts on that ground alone.
Arguably this incidient has no bearing on AmiBay, although we are here to trade, we are forum based as such libelous cases are delt with differnetly in the US and the UK due to our inherent transient nature. (unlike a billboard thats static)
I have to admit, I truly detest law, its the only subject that I study that unsettles my stomach to the point of wanting to barf.
whos idea was it to let lawyers MAKE law? - Its like handing guns and crystal meth to primary school kids