But now that I've looked at the piece, I bet the authors feel that they got mauled in response to their earlier report, so that may have influenced their choice.
The Greek letter theta, taking the place of the o in the Demos logo, became the eye of the Illuminati. As authors, we were roundly accused of being part of the conspiracy itself: at best unknowing, naive, and myopic writers; at worst disinformation specialists or government agents openly supporting state terrorism.
Yeah, some people say crazy stuff.
I agree with your argument more than I agree with what I take to be theirs. I'm not convinced that all their "hardcore" members are Manichean; I think some are better described in your words for the second group: "swayed (rightly or wrongly) by reason." Meanwhile, their "critically turned" group has a postmodern sensibility that doesn't seem quite to fit with any of your three categories. I don't disagree with them that that sensibility exists within the 9/11 truth movement; it might even best be construed as part of the hardcore. I think in 9/11 truth as in anti-vax as in climate change denial as in anti-evolutionism as in..., there is a tacit alliance between people who seriously think that they are doing good science and people whose main criterion of "good science" is whether it fits into their political analysis -- not because they intend to get the wrong answers, but because that is actually how they think about science. Probably people in both groups are disproportionately Manichean in some sense, although not entirely so.
I prefer your version not only because it somehow seems truer to my perceptions of the 9/11 truth movement, but because it seems more generalizable without animus. You know more about the skeptic movement than I do, so I will defer to you there. Just as there are climate change denialists who embrace excruciatingly superficial technical and political critiques of the scientific consensus, there are environmentalists who accept the consensus not because they understand the science, but because it affirms their assumptions about how the world is -- and some of them are anti-vax based on essentially the same assumptions. We're all somewhat at the mercy of our assumptions. We're not all exactly alike, but "they" aren't utterly different, either.