"Surely they could get something on her, if only to stop other muppets for doing the same."
There's really no point.
The threat of punishment works as a deterrent against people who are making some kind of rational assessment of the risks versus benefits of taking some action.
Imposing criminal penalties on crazy people for doing crazy things, does nothing to deter other crazy people; by definition crazy people are not really considering the consequences of their actions.
I guarantee you that the possibility of punishment did not in the slightest enter into the decision process (if you want to call it that) that led this person to open the emergency exit.