I would guess that the pattern of noncompliance and belligerence for many years had a lot to do with it. Their bluff finally got called.
Sleep in the bed you made. There is plenty to both sides of this long standing feud. Even family members of the ranchers gave testimony about poaching and the fact that one of the fires was set just hours after several deer were illegally taken on the very ground that was burned. Expecting to be left entirely alone by any type of rules or enforcement is just not a real expectation that any of us can live by in the modern world. The second fire was set during a burn ban for the reason that fire fighter lives could be put in danger. That was well known to all involved also. They didn't like rules, they didn't like the government, they didn't follow "rules". They lost. I don't know how they could possibly expect a different outcome.