LOL. The procedure for stamp duty is not computerised and linked to his pan number. He will have to physically declare those and he will not declare the money he has got in cash and will hence be black money.
No one cares how you spend your money, only about you whining that the Modi govt. do not allow you to indulge in generating black money. To expect any sympathy for that is just plain funny.
Nope .Now on he has to declare the source .
If he is able to instantly buy another property with that amount he can launder it without any issue .But if he is going to bank or even if he hides that in his house without any document it would be black .