it may sound a bit off the wall, but consider:
maybe bill is, consciously or subconsciously, sabotaging hillary's run for the roses? we all know bill comes totally alive in the limelight - he revels in it, it brings out the best in him. no matter how much he (allegedly) loves her, is he really ready to left go of Top Gun in his family?
bill's ex-presidency was going well. he was up there with bill gates and jimmy carter in world activism. he's make a great UN Sec'y Gen. but he drops it all to drop the race card in hillary's campaign. what kind of novice, let alone expert, would do that? he's risking his legacy - of vital importance to any former president. along with creating zero deficit, he'll also always be known as the nasty politician during the south carolina primary.
does bill want hillary to be president, to have more power than he currently has?
Maybe Bubba doesn't want to have to move back into her bedroom and play house again....