As I was told by VOA editors when I asked at the
beginning of the primary season, the Republican
presidential nominee should be referred to as George W. Bush,
while the 41st President should be referred to as
George Bush (or "Skippy," if you're in the mood
:P).
Hence, IMO, if George W. Bush is an answer to a
tossup or bonus, the moderator should prompt on the last
name - "George W. Bush" or "G.W. Bush" should be
acceptable answers. If the answer is the 41st president,
"George Bush" should be an acceptable answer, since he
was rarely referred to by his middle names during his
presidency.
James