Based on the way that string theory keeps on going like a zombie in physics, I don't think its disrespectful at all to consider allegations that are pretty much indistinguishable from those. Although I think that heavily entrenched groupthink and biases are all that is required. I don't think they're consciously think that "I need to lie in order to keep the research grants flowing" but its instead that old adage that "It is difficult to get a man to understand something, when his salary depends on his not understanding it". To an external observer those are largely indistinguishable and have the same effect, but in the latter case the person has convinced themselves of the lie or the half-truth via financially inclined self-deception.
I think there is truth to the general principle you refer to, but I don't think it accurately describes what I saw skimming experts' comments in the linked thread. I'm an outsider to medical research but have experience in other parts of STEM research at universities. Here I saw a plenty of nuance, documentation of historical skepticism, concern over broad perception, and plenty disagreement over technical points. Far from a unified kool-aid drinker sort of situation. And I think there has been plenty of changes of opinions in the Alzheimer's field in recent years given the number of failed drugs - which goes against the idea that these scientists are following their career over the evidence.
But people who are motivated by a decade or two of having their salaries paid by the leading hypothesis aren't going to produce unified kool-aid drinker kinds of rationales to support it. They've had decades to internalize the arguments and they will be nuanced and multifaceted. They're experts and their defense of the old paradigm will look just like expert opinion. There can still be rotten core foundations at the bottom of it all.
