Personally, I have little use for people who protest by occupying property that is not theirs and has nothing to do with the dispute. That goes for the Occupy movement of a few years ago, the current protest, and all the way back to the Vietnam War when protesting students staged sit-ins at campus facilities that had nothing to do with the war.
The sit-ins at segregated lunch counters during the civil rights movement were different. The lunch counter operators were perpetrators of the injustice at issue.
The main beef of the current occupiers is the violation of their constitutional right to graze cattle on land that does not belong to them without paying fees to the owner of the land, i.e., the federal government. I don't recall reading that in the Constitution, but maybe it's part of the "living document."