Technically, that seller can't even advertise their coin as "MS63", as its against
ebay's terms of use. In order for the seller to be able to state a specific grade number in the title, item specifics, or the description, it needs to be certified. If its not certified, the seller can only identify it by AU, Unc, Fine, etc. without the use of specific numbers. Not to mention that coin is so obviously not MS63.
As BullseyeBullion said, this kind of poor selling practice is what gives most legitimate sellers a difficult time.
ebay has a fantastic market for numismatic items, and as an
ebay seller myself, it's a shame to see listings like this that continue to downplay the legitimacy of
ebay dealers. Again, as Bullseye said, tell it like it is and your customers will absolutely love you for it.