My main reason for suspicion is my bad experience with a fake 1802 5K, which i bought, but was able to return to the seller.
The eagle looks very similar (to the fake i no longer have, but i will look for and post images), for example very even worn appearance with dull detail, and similar coloring. (based on photo only!) My fake also had the same slight offset striking, and "hollow" dentils on the obverse outer border.
If authentic, of course, it is a very nice rare coin.