The SLQ earlier dates wore off easily. The 6 looks too prominent to be a 1916. IMO, this looks like a Chinese fake made from a 1917 coin and the 6 was added to the fake die. Plus, all the other diagnostics mentioned above. Maybe, you should remind him it is a crime to sell counterfeit U.S. currency. Anyone he sells this coin to, if sent for grading or not, is going to want a refund and possibly revenge.
I have a few raw 16's, that one is a clear fake. Two things that always stand out on even the most worn 16 is a deep fold in the drapery above the "D" in GOD, this coin has it closer to the body, which is a 17. The other is the drapery that flows next to Liberty's right hip, the 17 has extra drapery so it looks like a "Y" as it meets the horizontal drapery, the 16 doesn't have this. So in the picture you provided, there is no deep draperty fold over the "D" and there is a distinctive "Y" next to Liberty's hip, either an altered 17, but more likely an Asian product where they based the design on the 17.
That statement up there is usually a good indicator that a coin is fake and by the looks of it. I'd say yep, it's a fake. Time to focus on something else.