I think he lives in Korea. Is US patent law even applicable?
It is if you try to buy or sell something in the US and get caught.
Even if you buy something and don't realize it, the goods can get confiscated and then you're recourse is to take civil action against the seller.
I'm no lawyer. But, that's my understanding anyway. Leupold deals with that constantly with Chinese knockoff scopes. ...although, they brazenly use the Leupold name and trademarks as well.