Seller is accusing me of mail fraud

Hello all, I recently bought a pokemon card for $22. Induced item, open it, and realized the item is not as described. The picture on the listing does not match the one I received. The centering was different which was fine for me, but the thing I did not like was that there was a decent crease on the back of the card and a little ding on the front. I messaged the seller about this and he immediately starts accusing me of mail fraud and saying I can return the card and he’ll then file a report with the USPS and the PD. I bought from this guy bc he had good reviews so I was quite shocked when he made the accusations. Just wondering what grounds he has to make this accusation and whether or not something will be done about it.