Failing to disprove Hume's Guilotine was the beginning of his problems. One that's really observable just by the practical application of natural selection. Then his application of his own philosophy falls apart from there.
Yes, he is technically against SJWs, but what he actually wrote was the SJW-lite position, which set the stage for his followers to use Da Science to completely bulldoze his objection. Which happened
in a Steven Universe PSA.
By the time he talks about determinism, the entire project breaks since determinism has the underlying assumption that people can't improve themselves or as he put it, "bad genes, bad parents, bad ideas, and bad luck [...] No human being stands as author to his own genes or his upbringing. [...] In fact, it seems immoral not recognize just how much luck is involved in morality itself" (109). If bad parents beget bad children, it creates an infinite regress of genetic immorality, which we can absolutely apply to the Black community. They definitely have bad parents and bad ideas, and to the Leftists, bad luck too. Can we then try to administer a cure to their genetic immorality as he suggests a paragraph later? Is Sam Harris a racist now? He certainly applies this standard to Islam since they also have bad ideas, bad parents (in his opinion anyways), and the bad luck to be living in the Middle East. Free will is a key component of all ethics because it makes the assumption people can do better than before. Really, what kind of message is it to tell your child that they can't be a better person than they already are? We see the results of that thinking with SJWs.
Combined with laying the groundwork for destroying constitutional rights, I've come to the conclusion that Sam Harris wasn't just a pretentious Atheist, but one of the people who laid the groundwork for the Moderate Left to slip into Identity politics. Sure, Derrida, Foucault, and Post-modernists introduced a bunch of obscurant nonsense into the Humanities, but he and the other Atheists contributed to the rot by accepting their premises at the speed limit.