I watched a US Forest Service officer arrest a shooter at Lytle Creek last month. (The guy 'left his bullet button at home'... oops.) Disclaimer: I've only been there a few times and am not familiar with whatever ongoing problems have been going on.
I'm not defending their actions, but imagine you're running a range (leased on BLM land I believe) and officers are patrolling your range looking for law violations. We're in a state with very obscure and confusing laws, with law enforcement, judiciary, and legislators all looking for an opportunity to stick it to anybody that crosses a line. I've heard stories of ranges being shutdown or closed down 'temporarily' indefinitely. Just the other day I read a post by somebody getting harassed on BLM land.
If I were in their position, I would be paranoid as hell. I would not allow something to happen on my range unless I were 100% sure that it was legal.
Having said that, it is their responsibility to know the laws and stop harassing people. Because they're on BLM land, to me it's different than a regular private range. Meaning, the right to make up your own rules is out the window.
You also have to consider that a range could be shut down and owners prosecuted even if no law was broken. There's a lot of 'interpretation' that goes on and getting it settled can be a lengthy and costly process. That's where the "fight" comes in, and yes I agree that it is worth the fight, but not something to step into lightly.
It would be nice if somebody well-versed in the laws with plenty of supporting documentation could have a sit-down with the manager.