Lawyers’ moral outrage tends to be attracted when there is someone’s money to take. Metzger and the Klan had legal assets to go after. Members of the “Black Guerilla Gang”, other street gangs, various Occupy and Communist groups, etc., likely own zero real estate or valuable assets, and do not have written contracts for their criminal enterprises. I do not know if Sharpton and his organizations have net assets, since the feds have liens on him for huge amounts of back taxes. Thus my interest in a connection to Nation of Islam, which is very analogous to the Klan, and does have assets.
But Swampsniper and others are correct. In theory, instigators of murder, riots, arson, etc. are subject to civil claims if you can connect them to the deeds. But pc double standards, jury nullification and intimidation, leftist judges, the Justus Department, etc., make going after black racist groups in court an exercise in futility.