There’s a few reasons that can occur, none of which have to do with the author. Discourse auto-pulls articles from the Spectrum website as soon as they are created, but it doesn’t pull everything (others have noted in the past that videos, for instance, don’t transfer over and unfortunately can’t be added in). Additionally, the author byline that appears at the very top of every Spectrum website article (and can be used to search through all of an author’s writing), never transfers over (and can’t be added in either).
As for this case, where the author bio at the end of the article was missing, it is most likely the case that the editor forgot to put the bio in the article on the Spectrum website, then realized the error, added it in, but the Discourse version had already been created. The website editors and Discourse moderators are not the same people (there is some overlap but not much), so unless we’re alerted to the error either by the editor or by an eagle-eyed reader, we won’t know something’s missing over here.
I don’t know if that helps clarify or just adds to the confusion (Discourse is a mysterious beast), but we’ll confer with the editor just to be sure of what happened, and in the meantime, I’ve added in Dr. Hemmings’ bio on the Discourse version.