In either case, him saying that admin wouldn't be able to help you in the worst case scenario where you loose your account, is pure bullsh*t, don't fall for it.
If he had DB dump, wouldn't he give your info on the "example" of userbase dump?
Mail coming from bitcointalk.org means nothing, it's a spoofed email origin, the guy is noone, trying to exploit naive users into some bitcoins.
cheers