That was the only thing I found surprising. I would have thought he'd leap at the chance to go after her. A lot of you never appreciated the fear Republicans have of the Clintons. Republicans thought if they went after her again, their base would reject them.
Knowing they could beat the Republicans fueled a lot of the support for Hillary. (That, along with deep-seated affection for her and nostalgia for the 90s, which you probably also can't understand.)
Until Tuesday, the Clintons were the only Democrats who could defeat Republicans. Now there are more. Yay. ;-}