I agree with what Ducimus said about it being human nature. This old gentleman lived thru that time and we do not know what he saw. He may have seen friends and family killed, may have even served on a merchantman plowing thru the Atlantic at the height of the Battle of the Atlantic. We don't know. So in that way I can understand some of his feelings. To him, that U-Boat may rekindle some of those memories and feelings. I'm sure there was a certain level of hate that the British had towards the Germans,but I don't know if it was ever at the level that Americans had for the Japanese.
My wife's dad served in the US Navy during WWII. Nothing glamorous-a radioman on a net tender(Always found it funny that he couldn't swim either-but that's another story). He was in the invasion fleet at Iwo Jima and has some interesting stories about that.
Anyways, my wife was telling me that he
hated the Japanese during the war, of course, and for a long time after the war. He would never buy a Japanese car and just about had kittens when my wife bought her first Japanese car when she was a lot younger.
It seems that he has since gotten over that hatred, but according to my wife, it was there and somewhat strong. I personnaly have not heard him say anything that would be deemed hateful to the Japanese however. Now at 83, it is hard to believe he could hate anyone. He is one of the nicest men you could meet and will talk to anybody about anything.
I've heard stories of other veterans hating their enemies for a long time, and sometimes taking that hate with them to the grave. It is hard for people that were born 20+ years after the war to truly understand that without having lived through it.
I always found it interesting how there was so much hatred for the Japanese in America during the war where there didn't seem to be the same level of hatred against the Germans. There seemed to be so much bigotry and lack of understanding of the Japanese, even before the war. the sneak attack on Pearl Harbor just intensified it a 1000 times over.
Part of the difference was probably the difference in Eastern culture and the Western culture that America and Germany was part of. We could understand the Germans as a people while there was such a lack of understanding of the Japanese culture and mindset at that time.
An excellent book that explains a lot of the history between Japan and America is James Bradley's "Flyboys". He goes back to when Captain Cook(forgive me if that is incorrect) makes contact with Japan in the 1800's to explain some of what led to the attack on Pearl Harbor. Very interesting.