One point that I'm surprised the post didn't raise: the notion that such groups are often able to claim authority because "this time is different". In true messianic style, the underlying genuine issue must be framed as both uniquely important and imminently approaching a tipping point. As such it is too urgent for observers to study the issue and form their own views - instead they must defer to the insiders before it is too late.
This strategy is all the more dangerous because, at least in the cases of AI and climate change, inaction does imply catastrophe and the consequences to civilization are vast and potentially permanent. When the diagnosis of the problem is perceptive, eloquent, and mostly accurate, people tend to assume the proposed solution must be right as well.
The clearest indicator of a priest-in-the-arena, and the associated social movement aimed at institutional capture, is the motte and bailey: implying and advocating for an extreme position, then retreating to a reasonable and harmless one when pressed.
(The crisis is coming - put me in control - we must change everything!) "Oh, you misunderstand! I was simply advocating for a sensitive and cautious approach."
Usually people back off from the extreme position when writing for public consumption. At least in that regard, the "AI-not-kill-everyoneism" camp is startlingly frank about reading the subtext out loud.