She doesn't want to answer the question about Obama, fine, then just say that. Her evasions and protestations would lead me to believe that she would have no problem with lying and stretching the truth to her constituents in the event that she were actually elected...
So -- the dividing line is somewhere between those running for high office, and the rest of us. I an accept that.
Of course, the question is easy for a lying politician to answer (once) -- as the answer is not verifiable. An honest politician (let's assume they exist, for the sake of argument), who also feels strongly about the "sanctity of the ballot box", would have a harder time answering the question. He might not want to answer to preserve the principle of ballot-box secrecy. You could have a situation of a lying politician appearing forthright, and an honest politician appearing devious. Oh, the irony.
It would be better to insist on release of verifiable information -- such as all the sorts of things Obama has managed to embargo. However, that raises its own problems -- as we saw in the Romney tax-records brouhaha.