You wrote: “At what point does free speech become subliminal hate speech?” Why, when you disagree with it.
You wrote: “Murray…publishes articles (albeit non-peer reviewed and discredited ones).” This is simply false. He has published numerous peer-reviewed articles as well as articles for a general audience, and his articles are not discredited merely because you or others disagree with them. It is in the nature of the academic enterprise for scholars to be disagreed with. The vehemence with which Murray is disagreed with is based on the controversial nature of his work more so than the lack of rigor that he brings to his work.