The poll, if you read the link, is backwards from what you would expect to support the result in the headline.
They asked "preppers," identified as such because they frequent the website, to tell what State they lived in and why. The results were then normalized to weight the response distribution by State population density.
As you point out, this method would drastically under-count any population who are "prepared," but for reasons other than those espoused by the Modern Survival Blog.