I think that the article might be misleading.
With 50% of potential buyers opting for iPad, it seems suspicious that Apple is missing from the other graph.
And what else did Amazon manufacture beside the kindle? As these would be the first tablets made by Amazon isn't it strange that 55% of the total number of people would buy a tablet from Amazon (that graph doesn't have any mention of excluding someone)? Isn't it possible that most of those who said that they would buy from Amazon were thinking of it as a vendor and not a manufacturer?