They didn't ask her if she was bi. :)
I believe that Hillary is one of those women whose sexual preference is "whatever gets me what I want." Right now that's being a straight, married woman with at least one child. If being a lesbian or bi or into dwarf tranny hookers was the way to power she'd be that. She's essentially asexual. Women who stay married to unrepentant tomcats like Bill Clinton usually are.