I generally analogize this with 9/11, which allows for a lot of nuance between the extremes of officialism and conspiracism. The conspiracist extreme would be that the US government itself did it, including controlled demolitions. But you could believe that the US government discovered an existing plot and improved it (ie, real al Qaeda hijackings but controlled demolitions too) or that the US government itself didn't do it but that it could have shot the planes in the air, or that intelligence had enough information to prevent it beforehand and purposefully didn't act on it. All of these are conspiracist to some degree, but don't imply that al Qaeda itself doesn't exist or if it does it is exclusively a false flag instrument of the CIA or other US agency.

Lone wolf attacks, of course, have a smaller gap where "moderate conspiracy" theories can exist, because the identity of the single suspect has very little room for doubt. And you are right that conspiracist extremes can be just as dogmatic as officialist extremes. But usually there always can be moderate interpretations of publicly known facts that adhere to neither entirely.