I don't know why they didn't just pass it over to WikiLeaks. They've been through that problem already, and have a process in place to delete that sort of stuff.
Lulzsec has had a history of defending WL (PBS hack for Bradley Manning), but I don't know if they are willing to give them this data as it might shine the spotlight away from Lulzsec.
Probably because Wikileaks' owner is a bit of an egomaniacal douche