That's against ebay policy. Report the ad it's probably a scam. If you contacted the seller through Ebay's messaging service then they will have a record of the conversation and ban the person if they are scamming people.
I sold that bike to that dealer back in February this year, and it stayed on his website for ages as still up for sale, when he had told me it had sold. From memory he explained that when someone interested called him up he would say its sold but I do have a nice mobylette that came in this morning😃 I think he just uses nice bikes as bait. I would not have a clue as to wether its legal or not, but certainly irritating!