The proposition is absurd on its face. The capacity to change positions without apology shows a willingness to pursue one's own advantage unburdened by shame and a certain level of naked ambition -- but that certainly doesn't equate with having the toughness and character to pursue the national interest unburdened by shame or ambivalence. That's especially true when you're dealing with a candidate who's happy to characterize following other countries as "leadership."
The essence of leadership is consistency in behavior and in principle. One can do business with foreign leaders most effectively when they can assume a certain degree of constancy in outlook and approach -- as evidenced, for example, by Ronald Reagan's handling of the USSR versus Jimmy Carter's vacillation.
Barack Obama's willingness to toss a promise overboard wins him nothing in the way of respect or admiration abroad . . . it merely serves to suggest to our allies and enemies alike that he's a man who will unblushingly do whatever it takes to secure his own personal political advantage. One can say what one likes about George W. Bush, but that's a charge that can never be lodged against him.