I doubt it's that simple, I don't know how CC works but is the seller assured they can buy it back for something close to the sale price plus some commission? If so, it's a way of getting through a tough time financially and being able to buy back the instrument?
Either way, and just to be clear, I'd say that all the same issues I've raised above would be a factor with anyone except a specialist business seller on eBay, Reverb etc - and even on BC - unless that is it was a private seller recognised as an authority on vintage instruments (there's a few on BC of course). I think we've all agreed in various threads on the forum that there are probably a lot of people out there who have paid over the odds for non-original and/or inauthentic vintage instruments, many of whom are likely completely unaware of the issues. You don't have to be dishonest to advertise a non-original/inauthentic vintage instrument, sometimes just not as expert as you need to be and unlucky enough - having bought one in good faith - to find yourself needing to sell it, which is not a great time to find that it's not worth what you thought. But this is also something that all buyers need to be aware of, as sadly, a 100% honest and trustworthy seller does not equal an all original authentic instrument.