I don’t know where you are getting your definitions - but the way visionary is used in the parlance of leadership is not how you defined it. I can define fag as cigarette or as homosexual man. You have to understand context, and clearly you did not.
What are you? Accountant? Bureaucrat? Lawyer?
Engineer. The way I see visionary used regarding leadership is “Visionary Leader”. But the noun definition of Visionary #7 I would have thought was a reasonable definition as you were suggesting to define it.
Since Santorum was taking a dig at his political opposition, the “context” clearly suggests you should take one of the negative connotations of “visionary”. Your argument that we WANTED a visionary assumes the positive definition of the term, which would be inapplicable to the context.
Which was the point I was trying to make in a humorous way — that there are many definitions of “visionary”, many of them have a negative connotation, Santorum was using that negative connotation to take a mild dig at Gingrich, and those who claimed he was saying he had no vision were the ones taking the comment out of context.