I think Chris' idea holds quite well, if we choose to look at it that way( I mean by seeing Shelby as the MC).
For me though, it further argues for Miles being the MC because there's only one inequity as far as I know (from the theory). All the throughlines are distinct perspectives on that one inequity.
Also from my limited knowledge about subplots(non-Dramatica), they run parallel to the main/A plot, never really intersecting with it per se. Plus giving context to an IC's "personal" life comes off as storytelling(using Armando's technique of creating subplots from character relationships from the build characters screen). However it doesn't seem to have a well defined argument, but then again it might as well be a tale.
The "I" POV is experienced rather strongly from Miles' perspective.
What do you think about the movie?