I'm not going to get involved in an argument premised on a clear misuse of terms.
... then on what basis can similar extrapolations on his work to the "racial struggle" be refused status as Darwinian in type simply because you disagree with their conclusions?
Darwin used the term "race" interchangeably with "species" and "sub-species," (or variety). Regarding humans, in disagreement with most educated opinion of his day, he clearly concluded that all humans were the same species. His biological theory has no connection to the racial prejudices of other people -- except that other people may claim such a connection.
Some quotes from Darwin that the Nazis would certainly have agreed with:
"A tribe including many members who, from possessing in a high degree the spirit of patriotism, fidelity, obedience, courage, and sympathy, were always ready to aid one another, and to sacrifice themselves for the common good, would be victorious over most other tribes; and this would be natural selection."
He was apparently not opposed to the idea that natural selection also applied to human groups.
"Many races, some of which differ so much from each other, that they have often been ranked by naturalists as distinct species."
"At some future period, not very distant as measured by centuries, the civilised races of man will almost certainly exterminate, and replace, the savage races throughout the world... The break between men and his nearest allies will then be wider."
The Nazi program in a nutshell, presented by Darwin as inevitable. He also pretty clearly viewed the "inferior races" as closer to the apes than us superior beings.