I would certainly suggest that the wording be altered that references his "bestselling author" status, since as a non-US citizen I hadn't even heard of him before I started researching Mormonism to a deep degree.  I feel it's quite "weasel-wordy" to say that he's an American author and then say separately that he's a "bestselling author" because the way that is done implies he's a bestselling international author, which clearly isn't the case judging by the fact that Amazon.com rank his book #25 out of 100 in the category "Mormonism: Controversial" and only in the late 617000's as an overall sales rank.