My understanding is that, as stated in the quote, carry is allowed if the state the park is in allows it... except that all buildingsin the park ("Federal Buildings") are off limits, including restaurants, shops, etc... Not sure about lodging... if government run/owned, then off limits for sure.carry is allowed in all of them consistent with any state regulations but discharge, for any reason, is prohibited. I guess that means if you hike through the Big Bend and get attacked by a mountain lion, you need to use rocks or sticks to fight it off?
If you are attacked in the park (animal or human) "necessity" is usually an available defense. I believe (again, opinion) the "no discharge" rules are more about no target shooting or hunting.
Did I mention this is only my OPINION!??
EDIT: Necessity defense is a question mark...
https://lawreview.uchicago.edu/print-ar ... iminal-law
https://www.losangelescriminallawyer.pr ... ssity.html