In that point of his life he was in the US, he did originate from Germany so that explains the accent.
But surely it's not that bad? Perhaps you dont hang around many people with accents, I don't know, but what I do know is that his english isnt all that bad aside from the fact he mispronounces a word or two now and again.
The way of the warrior is a resolute acceptance of death. -Musashi