I'm not sure how useful these data are, excepting some of the market perception stuff. The "would not buy after owning an iPad" part is oddly phrased and doesn't appear to consider how many "would buy without owning an iPad".
However, since the iPad is an ebook reader, I'm not exactly sure what the issue is. After buying an ebook reader, some people don't want to buy another one. Seems reasonable, though a bit out of character for the Apple buyer stereotype.