Resistance to the federal landgrab was growing. As Finicum describes in this video, they were educating people about the unconstitutional land grabs by the feds. Seems a reasonable motive for the feds to want to keep the ringleaders away from the meeting.
The article below incorrectly puts the sheriff at the scene of the roadblock, but, as the comment explains, he was at the meeting as an observer. Apparently he did not arrange the community meeting but was participating until he got the news about the killing when he left to go to the scene.
Was the Killing of LaVoy Finicum an Assassination?
It isn't over as this release from Reuters indicates:
Family Alleges Cover-Up of Finicum's Killing