On the one hand, it's definitely a shocking display of innumeracy. I sometimes find it difficult to tell the difference between genuine innumeracy and just people who aren't as mathematically inclined as I am, but in this case, I think that this is a definite case of ignorance above and beyond.
As a card carrying mathematics advocacy nut, you'd expect me to be shocked at this, and indeed I am. I'm somewhat disturbed by the feeling of schadenfreude I'm picking up from a lot of people commenting on the story, though. The main reaction I'm having to it is despair over the state of our education system. If the woman reported in the story doesn't understand negative numbers then that doesn't mean she's stupid (though she may be); it means that she's poorly educated.
I'm not sure where I'm going with this, really. I'm just feeling very conflicted about the story.