Dead-end cause. They're not getting public support because they're unable to succinctly define the injustice to which they object and whatever solution they propose in a way that makes anyone give a shit. As far as I can tell they want to make more money by having their cows eat government grass so they're arguing that the government doesn't have the right to manage the land. And that this is tyrannical in some way.
At most, it'll make people go hmm and undertake a scholarly investigation into the constitutionality of federal land management versus a state's right to make the rules. They'll never inspire a visceral reaction from the general public and gain popular support with this. There's no egregious injustice that's going to serve as a rallying point in this academic investigation. The attempt to manufacture one by framing the arsonists as martyrs is transparent and off target. Again, it has to be explained to people. There's a bunch of legal minutia swirling around. It doesn't work. You need something that's immediately obvious as unjust and makes everyone say 'no, fuck that' as soon as they hear about it if you're going to win popular support for your cause. They don't have one of those.
I don't have any strong feelings either way about whether a state is entitled to a more active role in managing the land within it's borders. I just don't care. This whole thing looks to me like a rich man's cause anyway. The ranchers with their thousands of subsidized acres and millions of dollars worth of stock and plant are shitty because they could have made $10 mil last year instead of a lousy $2 mil if that meddling federal government hadn't come along and told them to stay on their own land. Baron Von Derp really expects all the $7/hr guys are going to form themselves into ranks for his cause?