You are committing the slippery slope fallacy. In you case the slippery slope fallacy would go this way, "If we let Charles Murray sell his books eventually in the United States people will will be turned into soap and lampshades."Again, because we know where that kind of thinking leads. It leads to people being turned into bars of soap and lampshades. The Germans have got it right, this kind of stuff is banned.
The slippery slope fallacy is a fallacy because the slope is not slippery. We can stop at any time.
I am confident that the books of Charles Murray and Professor J. Philippe Rushton will not lead to the extermination of Negroes in the United States. I do hope that they will be cited when the United States Supreme Court takes up the issue of affirmative action in hiring decisions. I hope they are used in arguments against racial reparations.
You are also committing the guilt by association fallacy. In this case the guilt by association fallacy would go this way, "Because the Nazis were heriditarians, all heriditarian books should be banned."
I do not even think Mein Kampf should be banned. I have read it. I still admire Jews, respect Judaism, and love Israel.