His particular flavor of sovereign citizen was Washita Nation, a black nationalist group given to crackpot racial history of blacks as original inhabitants of the US Gulf Coast region. The sovereign citizen element is a thin veneer over the group’s core beliefs, which are all about black separatism and territorial entitlement.
Though some others here do treat this group as more legit, I'm thinking they're all a bunch of nuts, just from various trees!
Long's particular branch seems lean toward violence and mayhem!
Someone with psychiatric background might refer to him as paranoid schizophrenic!
It takes all kinds (of paranoid race cults).