"Because of the federal government shutdown in the US, all national parks are closed. This has been widely discussed in every form of news media - tv, radio, online, print - so it's odd that she hadn't at least heard of it."
The teacher's comments indicated that she didn't think that "closed" applied to the area at large, only to the facilities that would be run by employees, and that's not a completely unreasonable belief. To be honest, a lot of the signage I saw pertaining to the park closures didn't explicitly say that the area was closed (a barricade saying "Closed" but not "Do not enter" is a badly marked barricade in my opinion, especially when it's not laid across the entire entrance road). So it's still possible to know about the closures and not think that it meant that you weren't allowed past the gate. Her SSitude sprang forth when she commented that she was going to look up the citation to see if it was real, because the citation's existence should indicate that she broke a real law.