Barry "Goldwater" Obama doesn't want to debate Messalina Agrippina, because Messalina Agrippina would knock him out, and quickly.
That's Barry "Goldwater" Obama's biggest weakness, by the way, for the general election campaign; he wouldn't last five minutes up against John McCain.
The deal is, Barry "Goldwater" Obama doesn't have any experience with this sort of confrontation, what with journalists and debate moderators being very careful to ask him only softball questions.
The questions Messalina Agrippina has for him--or John McCain if God forbid Barry "Goldwater" Obama's the Democrat candidate--would be like throwing bowling balls.