This raises a related, but much tougher, issue.
Does free speech include false speech? Does it include misleading speech? White nationalists are not known for telling the truth, the whole truth, and nothing but the truth.
Does free speech allow them to make up claims about raping children? Should someone be allowed to make those claims in a college classroom? Should someone be allowed to present photos of child rapists, but only people of one race, without even acknowledging the existence of the other child rapists? This quickly becomes the dominant issue when you go down this road. I find the naive "pro-free speech" stance to be unsatisfying.