I'm personally uncomfortable with Holmes because of Buck, but it does have to be remembered that in the interwar period eugenics was the definition of a consensus issue, almost to the point of being a settled one. Only some (but not all) Evangelicals and Catholics and some (but not all) socialists and anarchists opposed it. Even early disability rights activists (Helen Keller, for example) sometimes supported eugenic measures against disabilities other than the ones they themselves had! It was a terrible consensus that lead to some of the worst atrocities in history, but it was a consensus and I'm not sure Holmes in particular should be singled out as uniquely responsible for it.
As far as I recall, Wallace was the only major evolutionary scientist to oppose eugenics until Dobzhansky - a significant amount, if not a majority, of opposition to eugenics was led by WJB & others who disputed evolution itself.
