Such hateful ideas are a symptom which can have wast variety of root cause. Your example is quite extreme and I agree it rightfully warrants hatred, but I’d argue that it’s all the more reason to not dismiss a person. We should seek connection with and understand these people and prevent destructive ideas from spreading IMHO, because there will be others who also won’t dismiss the person - only difference is that they might be receptive for hateful ideas. Sorry if I came across supporting these ideas, this is not the case.