I don't understand why anybody would be interested in purchasing large amounts of BTC from you when they have endless options that are safer with more reputation. You didn't mention how many coins you have for sale, you did not mention a rate or why you are selling them in this manner. There are too many questions, and too little effort being put into your "proposal".
If this is not a scam, which I doubt, my guess is that he want to deal P2P and don't pay taxes for converting crypto into fiat.
BUT I suggest everybody to stay away. If you are converting fiat to crypto, you are from the winning side of taxation.