"That part about not firing a gun in Death Valley for any reason, does that mean you have to let some thug beat you to death rather than using a firearm?"
Technically, I suppose it does mean that, but what it practically means is that the NPS may now have to swallow the exercise of your 2A rights, it doesn't change their prohibition on plinking, hunting, etc. in the parks and monuments. I can't help but notice that in most part, national parks and monuments have been remarkably free of the gunshot vandalism endemic on public lands throughout the west.
I'm doubtful that armed resistance to an attack by a human thug or an animal is going to result in a prosecution for a firearms offense.
I also agree that there's no point in intimidating tourists by open carry in "public" places, where carrying concealed is an option.
Do we need to start another bear/cougar/thug park-gun thread???