I'm given to understand that they (that is, the person who'd purchased the cards) did, in fact, have them legally. A retailer breaking the street date for when something goes on sale, even accidentally, is not an issue of criminal law, and even if it was the penalty wouldn't fall on the customer who received the embargoed set of cards.
Like I said, I don't follow MtG much. Knocking on someone's door, asking for a product they should not have had and replacing it with another set (something they did not need to do) just simply isn't mafia levels of intimidation like some people claim. It was also an isolated incident. One, admittedly I don't understand because I will never get why people are so passionate about a trading card game. Then again, there are a lot of things I don't understand like why people love football or why the NFL is categorized as a non-profit organization.

Does anyone remember how TSR threatened to sue everyone under the sun for any perceived sign of infringement? Do people expect corporations to never make a mistake or be completely altruistic?