I think a better title would be Dark Arts: A Case Study. I came here expecting a lesson in how to use the Dark Arts. But a lesson should consist of more than just pointing out an example, broader arguments and suggestions need to be made.

It is not here because the book is important; it's here because it describes an example of a deceptive persuasive technique.

You talk a lot about Steiner's use of the deceptive technique, but not a lot about the technique in general. I feel it would be better if you talked about the technique in general, how to recognize when it's drawing you in, other cases where it is used, things like that. A specific instance of Dark Arts by itself is not a noteworthy occurrence, the Dark Arts are used all the time across the planet.

A point you propose to establish from a single example. Now since philosophy appears to have much the same problem as LW comment threads - people trying to signal intelligence rather than find the right answer - the institutions you mention could correctly assess status based on this (never mind the long tradition of respecting bad arguments for religious claims). You have yet to establish that Steiner's argument persuaded anyone.

Still, in the interest of not making this comment self-referential: your central claim seems somewhat plausible.