From your first proposition, it seems what you mean by "beautiful" is the physical appearance of people, because if you meant spiritual beauty, it would be contradictory to believe someone can be spiritually beautiful, but not necessarily good. Therefore, I can refute your second proposition: What is your logical basis to argue that Nelson Mandela, or Mother Teresa were beautiful people?
Isn't beauty in the eyes of the beholder? Isn't it relative to your cultural context? What if someone believes long necks, or white skin, or curvy bodies are beautiful? Can they still believe these people were beautiful?
What the topic mean is that when a person is gifted with beauty, he/she is rarely gifted with intelligence and smartness. Or you can say that beauty (physical off course) and folly are generally companions. Mother Teresa, indeed a very charitable person was not at all a beautiful face. Nelson Mandela, also not an attractive face but certainly a beautiful soul. Beauty and folly go together. Miley Cyrus certainly go with the statement.