Again, I don't see what he did in that way at all. I don't think he "sought the heart of the mystery by using logic"; his approach to movies, in my opinion, and according to what he said, not only in those clips, was to see them as a scary amusement park ride -- what matters is the emotions in a moment-by-moment basis (and that is indeed Si), not so much the plot. Now, of course a movie must have a script, and they will have the "mystery", but that aspect of filmmaking did not seem to interest Hitchcock at all; in fact, I think he always discussed his movies from the point of view of how to construct particular scenes, not really from the point of view of the plot.
Again, why do you think that "figuring out how best to come at answers, seeking the heart of the matter in a mystery by using logic" particularly interested him? He did not seem ever to discuss his movies from that point of view - rather, again, on how to construct individual scenes. And that is related to Si.