Yes. Both his father’s parents were born in Germany. To refer to his father as German is just normal language usage. People do that all the time to refer to their ancestry without implying that they were born there.
You mean like African American!?
It’s the way Americans talk about their ancestry. My mother was 100% German, but she was born in the U.S. Her grandparents were born in Germany and immigrated. People on my father’s side go back before the French & Indian War. Jackasses don’t understand America. They stink of foreign influence.