Most "ist" words have lost any meaning because they have been overloaded with exceptions.
For example, terrorist apparently can't apply to armed white Christians who use force to take over a building owned by the US government. If they had been a different race or religion the word would have fit. We need a word that's equivalent to terrorist to describe white Christians who do what terrorists do.
I don't think they used force, I think it was unoccupied, and they just went there and hung out there peacefully to raise attention to the mistreatment of some ranchers by the government. Not too much different from the Occupy people really, other than the fact that they didn't vandalize anyone's property.