Oh Amaterasu, please. No.
The Secretary obviously cannot avoid this appointment, if the Asō government seeks to arrange it. To refuse to meet with the abductee families or even "have no time in my busy schedule" for them would be disastrous. It would be the ruination of the visit and possibly Secretary Clinton's entire relationship with Japan during her term in office.
I have this fantasy, though, that Secretary Clinton turns the Aso Government's attempted squeeze play into an embarrassment...
"Minister Nakasone and I also talked about the issue of those abducted by the DPRK, whose families I had a chance to meet yesterday. I told Minister Nakasone that the United States will never forget the families and will do its utmost to seen a resolution the abductees issue. I told him that as a mother of a child more precious to me than life itself, I would never forget the terrible crimes dones against these blameless individuals. I then urged Minister Nakasone to reinforce Japan's position on the abductee issue vis-a-vis world opinion by signing The Hague Convention on the Civil Aspects of Child Abduction, thereby bringing Japan's practices and laws in line with the 81 other other signatories to the Convention, and immesurably strengthening Japan's hand in its negotiations with the DPRK."
What's good for the goose is good for the gander, or so they say.