Sidis may have ignored mentioning Jung because he was approaching the unconscious from a direction that was not necessarily opposed to Jung, but in a way that might not have been supported by Jung, either. The main point that he was trying to make, if I recall the article correctly, is that the unconscious, rather than being blind and dumb, is actually possessed of far more intelligence (i.e. - consciousness) than we ordinarily ascribe to it, and that it can observe, make deductions, comparisons, etc. without "us" being consciously aware of these processes. The very acts of PhotoReading, dream recall, psychoanalysis, the Silva Method, Image Streaming, etc. are attempts to make the unconscious conscious. So are the ritual methods of a number of aboriginal religious/magical practices.
The problem with any psychological theory is that it will probably never be complete. I think that the mind, metaphorically, is like an infinite room of mirrors - whatever you put in there will be reflected back for you to see. Most psychological theories probably hold a grain of truth to them, partially because they might describe how the mind really works and partially because the mind accomodates the theory. Biologically Adaptive Lexical Learning Systems (B.A.L.L.S.) are a pain that way. :-)
I believe that the PhotoFocus state allows for a "diffusion" of consciousness so that the mind remains in an alpha-theta state, as opposed to beta, while PhotoReading so that the material makes a deeper impression in the inner mind. PhotoFocus is not as difficult a state to attain as people make it out to be. My comment was meant to perhaps shift some of the emphasis that people place on the PhotoFocus state away from that state and onto learning how to pick up on their own inner promptings. We continually pick up material peripherally throughout the day. The PhotoReading step has a lot to do, I think, with picking up material from the page peripherally. The tough part, if there really is one, is getting the information out of our heads once we get it in there. The funny thing about that, however, is that when the "knack" is learned you find that it is really simplicity itself - you simply play and allow it to happen. The inner mind "desires" to help the outer mind. It just needs to be consistently told what to do. It also needs to be listened to and acknowledged on a regular basis (though not always followed - the outer mind's job is to weigh the options that it gets from the inner mind after the "messages" have been received").
One thing that I think would be of enormous benefit to PhotoReaders would be Silva Method training. You can get a home study course for about $50 and the long term benefits, once the system is integrated, are beyond measure.