Sorry, but there is no such thing as "universal behavioral science". Psychology is a soft science, built upon hard sciences, (such as mathematics, biology and physics), as well as other soft sciences, such as sociology. Dissonance theory is no less a valid area of study than most any other area of psychology. Actually, it is more "universally" accepted, than many other areas of psychology, since it does a very good job of explaining a complete picture of what is actually going on better than its competing theories.
While what you state concerning the two conflicting thoughts existing at the same time is the dissonance, you are oversimplifying the contexts as to how and when this dissonance is experienced. Most of the time, it is not acute. It exists mostly at a subconscious level, and rarely causes much interference with normal life. Brief moments of discomfort are experienced, (such as watching a nature show on the reality of evolution, and stating "well I know that part is false"), and the dissonance resolved through that denial.
There are times, (and pointing out a GB member's gaffs is one of them for sure), when acute CD is experienced. The discomfort is immediate, painful, and triggers a response that could only be described as absolutely illogical. The alternative at that moment is to either accept the possibility that one's belief system could be wrong, (and hopefully investigate further as to why), or shut down. The latter is almost always chosen, because very deep existential fears would need to be overcome instantly, and that is likely not humanly possible for most. Cognitive dissonance cannot save one from such a state, so denial is even more likely in this acute state of CD.
I agree many ex-JWs misuse this term. I am not one of them. I think you use it correctly, even if your take on the science being somehow less valid than other areas of psychology is simply not true. Where I mostly differ with you, is in the black and white approach you are taking to when this dissonance is experienced. It is not "one and done". It is ongoing, (usually in the subconscious), and at times becomes acute, when evidence is directly presented to the conscious mind.
d4g