The formal term for this fallacy is "appeal to authority," and it is among the most common fallacies you see in the citation cartel. Anyone interested can unpack the arguments made by Ferguson and Sperry; I find appeals to authority not worth the time and effort. Note that this fallacy is a different argument than an appeal to authority based on special credibility, such as a witness (which is why we publish the testimony of Joseph Smith and the 3 and 8 witnesses in every edition of the text). The appeal to authority fallacy applies when the cited authority has no more unique knowledge or expertise than anyone else. Any member of the Church can assess the same evidence that Ferguson and Sperry did and make up his/her own mind. There is zero reason to defer to them (or any other member of the citation cartel) on this issue.