It's not illegal for him to sell.
It IS illegal for you to import it into the US.
It's foolish to buy a 'rare' coin from somebody who makes their living selling "High Quality Mini Cute 4 Hole 8 Tone Harmonica Necklace Fashion Jewelry"
-----Burton
50+ year / Life / Emeritus
ANA member (joined 12/1/1973)
Life member: Numismatics International, CONECA
Member: TNA, FtWCC, NETCC, EveryCountry (online) coin club
Owned by three cats and a wife of 40+ years (joined 1983)
Author: 3rd Edition of the Sample Slabs book,
https://www.sampleslabs.info/