facepalm
1. Is there "a US law" against receiving unsolicited product."
First, there is no "US law." The US is a law of many jurisdictions- the main two that most people are concerned about are STATE and FEDERAL. So when people look this up, they often completely misunderstand the issue. If something is given to you (an unsolicited gift, for example) then you have no obligation to return it under federal law (interstate commerce). This doesn't necessarily mean that you are okay under state law, nor does it mean that you are free from civil action. But more importantly, people are asking this question in the context of the rise of scams and/or free products directly sent to them. This is all about people who get sent scam merchandise and are then ordered to pay for it. You can't use this if, for example, a product is addressed to someone else. Or if you bought stolen or counterfeit merchandise. Or if the goods are illegal ("Hey, officer, I know I got a brick of cocaine, but it was unsolicited product! You're cool with that, right?"). Or if there are any number of state laws that you might be violating.
You made a blanket statement- here it was:
I looked up "unsolicited goods".
Apparently (at least according to US law), receiving an unsolicited product from a company and keeping it is not illegal, so this isn't exactly a case of stolen goods.
I explained to you why your statement isn't correct. You likely came across this statement because you googled it, and found websites discussing the issue in the context of the rise of scams- people being sent unsolicited products. This may shock you, but this does not actually answer the question presented, and I gave numerous reasons why, including a colorful example that everyone should be familiar with. In other words, you provided a "rule" that was incorrect- which is easily understandable if you think about it for even a second.
Moreover, the "rule" you're thinking about it simply the general rule about gifts- if you are given a gift you don't have to return it- whether the gift is from a corporation or a friend. But there are all sorts of "things" that go along with that idea that do not apply- and, for that matter, you can still be held liable (civilly and criminally) for a gift ... which this wasn't- no one is saying that Hasbro knowingly sent him an unsolicited gift. I could go into more detail, but that should suffice. The lesson, as always, is unless you have some background and understanding, it's best not to try and generalize legal principles based on a quick internet search.
But it's pointless to keep going, because if you don't understand basic background principles (like the difference between federal and state law and why that matters) then there is no point in this conversation, especially because you simply want to get to a predetermined conclusion.