"preaching that everyone who is not them should be killed off is counter to species and individual survival and should NOT be tolerated."
You mean like this:
Black man advocates [final] "solution" for white people on c-span
http://www.freerepublic.com/focus/f-news/1502842/posts
Yup. That shouldn't be tolerated either.
If a man walks up to you and says that he's going to kill you and your family, many states allow you to shoot him on the spot if you believe that he might carry out that threat. Why should people who band together to threaten others be treated any differently?