Great find, slimboyfat!
the belief system of Jehovah's Witnesses has made use of the defense mechanism of multiple endpoints and deflationary revisions
I would add that this defense mechanism wouldn't work as well as it does were it not for the highly authoritarian structure of JW's belief system, which is enforced and re-enforced over relatively minor matters, like recreation (see, for example, last week's WT study) so that JWs become conditioned to accept "deflationary revisions" in major matters. When a potential crisis of belief in the form of failed prophecy occurs, they default to submission (of independent thoughts) and exultation (of whatever the "slave" says) that has been so thoroughly ingrained in them. For example, ask any JW about the recent change in "generation" and invariably they will trot out the old saw, "the light gets brighter" as a reflexive deflection any "disconfirmation," handily supplied by the "slave." So while the rationale of multiple endpoints and deflationary revisions is certainly at work, it rests on that foundation of unquestioning obedience and practiced rhetoric already in place.
I think "self-validating" refers to the process by which beliefs develop resilience and persevere. Those beliefs, as the author explains, that are flexible enough to allow for revisions of the kind described, have a better chance of surviving and, by surviving, tend to strengthen themselves in the minds of the believers. A great example is the latest "overlapping generation" of 1914. When the FDS gave that explanation as a way of rationalizing the seeming failure of its earlier definitions (deflationary revisionism at work), JWs were primed to go along with it because of their overall conviction that the generation of the last days/1914 must be a reality in some sense (to paraphrase the article) AND because of their conditioning, and so the belief about the generation of 1914 is reinforced for JWs, albeit in its revised form.