Perhaps the account was for sale ('on the darknet' as mentioned by the second, current hacker), The email could have been from the first hacker that sent the 'not Dorian' message, and subsequently access to the account bought by this new guy, who wants to make back his 25 BTC so he doesn't take a loss on the purchase of the account.
Keep in mind that he won't say how he hacked it but brags about everything else, quite possibly because he simply didn't.
Also I would doubt someone as immature as the hacker appeared to have been would have had access to the resources to pay 25 BTC for the credentials to his email account