There’s a third reason too: she wants to run for Pres in 2016 and doesn’t want to be as closely tied to Obummer as a VP would be.
Can’t say I’m surprised that Hillary has more balls than Obama or for that matter a lot of people in his administration.
Plus you have to remember that Hillary had her own close call when her husband refused to accept Osama when the Ethiopians offered. Had to send Sandy Pants Burger in to destroy the evidence.