Yes they are scans as you supposed. I do not have the camera equipment to take better shots, and the only option on the scanner is to double the dpi - which runs into the picture size limits!
One day I will get into better photography but at the moment my cash is spent on the coins, not on photographing them. :-)
If it was just the one, and they'd looked at the lot, rather than stopping at the first one they found, then it's only a 0.08% find rate, and probably quite representative as it was a fair sized sample. Either that, or there were more, but they were so good, they escaped scrutiny.