I know your position on this, and am not trying to convince you to do otherwise. However, the question also remains if the law is the same everywhere.
Besides, the situation is quite complicated. The publisher has contract with the seller not to sell to non-US customers. But does that mean that any such sales that do take place are illegal, meaning ownership is not being transferred? The seller may be doing something illegal, but he can claim a good faith effort if he took reasonable precautions. Would the buyer aquire a legal license if the seller knew the buyer was from outside the US and the buyer never claimed he was a resident?
And there are many similar situations in the physical world. Let us say a seller from France sells a car to you in the UK -- and ships it to you from France. He has a contract that he is not allowed to sell outside of France. You take care of the import formalities into the UK. You are the legal owner of the car, aren't you?
How would the situation be if you traveled to the US and downloaded the file while being over there? What if you use a VPN? Aren't you actually using a computer that is physically located in the US?
In the end, why should a contractual agreement between the seller and his supplier bind the buyer?