That was a curious and sort of out-of-charater description from a Senator who has advanced himself by being able to convey detail.
Westly is either just as hollow as the Senator describes or, and I'm always suspicious of everything politicians utter, Westly bears watching since he has a limited public track record.
McClintock has been around too long to misunderestimate Westly. Remember that these comments were made before friends, not for the general public and are more relaxed in nature because of that.
The term "empty suit" doesn't mean stupid; I think of it as equating to "a person motivated by ambition and pride to such a degree that one needn't look any further to understand their actions."