In a word: duh. However, I do not for a second think that you would not listen more closely to someone like Stephen Hawking than you would a guy shouting "Prais

In a word: duh. However, I do not for a second think that you would not listen more closely to someone like Stephen Hawking than you would a guy shouting "Praise Jesus" on a street corner. There is no fallacy involved here. If Hawking is speaking nonsense, his being Stephen Hawking is not going to save him.