Joe Kennedy ( father of Ted, JFK, and Bobby) was pro nazi too before the war. The fact is for a long time quite a few people hid their head in the sand about the true nature of Hitler and the Nazi party. Anti semitism was alive and well in America as well as Europe at the time, how the hell do you think Hitler came into power in the first place?
So regardless of what Bush Sr's fathers prewar views were, the fact is GWB sr. was a Navy Airman who risked his life fighting for the American cause in WW II, just as Joseph Kennedy's son's served with honor in the same cause. In fact Joe Jr. made the ultimate sacrifice for his country, so perhaps that's why their bad pre war judgement has been glossed over by historians and not been used to tarnish the careers of their legacies.
I loved my father, and he was a good man, but he came from a different time, and I wouldn't want some of the viewpoints that he held earliar in his life attributed to me.