WP:WEASEL only applies to what Wikipedia editors write. It is wrong to write "[The general impression of Wikipedia editors is that] the After Death misconception is widespread enough that it needs to be pointed out." On the other hand, an author entrusted by a recognized publisher to write a book, thus putting the reputation of the publisher at risk, is entitled to write about his general impressions of what misconceptions are worthy of mention, and Wikipedia editors are entitled to put the author's general impression into a Wikipedia article. It is nonsensical for a Wikipedia editor to attempt to impose Wikipedia's internal guidelines on an external author and publisher. A sufficient source has been provided; the burden is on Zargulon to provide a better source before disturbing the article any further (unless he/she wants to edit to make the article more closely follow one of the sources provided).

As for not needing Ryan, we don't need him to establish that AD is not an abbreviation for After Death, but we do need him, or a source like him, to establish that enough people entertain this misguided idea that the idea is worthy of mention.