I have not read it. But I think that the manifesto should be read and talked about. Given that so many people are conducting mass shootings, it is important to understand why. By not discussing what angers these people, we are ignoring the sociological causes.
In this case, the shooter was not crazy. Perhaps he was sociopathic — we don’t know. But he had many fears, and he tried to articulate them. Even though his actions were reprehensible, and his values might have been despicable (perhaps racist — I don’t know), we need to know what is making people so angry.