Wouldn't apply in this case. I'm certain that if Amazon.com sold bitcoins to a Visa customer, Amazon.com would either be able to prove that they sold it to the correct person, or simply didn't engage in the transaction. Said another way, Amazon.com has the ability to verify that their customers are who they say that they are at the time that they order anything.
That doesnt change the fact that Paypal or Visa would either have to change their policies on currency trading or officially take the stance that bitcoin is not a currency, but a commodity. The implications of that would be significant, as everyone could start accepting credit cards for bitcoins by proving their transaction and identity (using orders that include visa card number signed with their private or something like that).
That's a fair point.
