This case is just for show IMO, unless they want to keep coming to court for the next couple years.
The main problem of the US and their law is that while all countries believe that if your citizens go somewhere and buy something, they need to check if it's fine with their local law. So if you buy a gun in an online store and your country doesn't allow guns, you will have to take responsibility for it and possibly face a fine and lose the gun.
The US law makes it so that if someone buys a restricted item online, it's the fault of the seller. The seller should have asked where the client is from and be aware of all the US laws and regulations. Tell me this isn't crazy.
No it's not, if all the seller has to do is just asking the client about the legality in his/her place. It would be, though, if the seller would still be responsible in the case of customer's lying.
Regarding the article, I personally think that the platforms shouldn't be liable for what's selling there, but it's the law, so, we should comply, I guess.