Technically it was a 3rd party seller right? Like eBay or a flea market or the back of a truck?
Technically, yes. But Amazon's site doesn't make this clear.
Yes, but you still pay Amazon, and Amazon pays the seller. Using a virtual card wouldn't have helped him here. The other victim wouldn't have been helped by using a virtual card at Walmart.ca either.
A virtual card that expires or is limited would have protected somewhat.
No, because the order would still have gone on Walmart.com with his real name and address