Real question- what is a "racially pure German"? Germany wasn't created until 1871, from 300 unique states.
https://history.state.gov/countries/g...Who decided this and how? The origin is people wanting to be part of the majority: people's whose families were from a city-state for 1,000 years are all of a sudden "German".
Rosenberg is a tough man, mentally and physically. Sorry to not give him more focus.