KB-
I largely concur with your observations.
In fact, LBJ's directive to the WC, to pursue the LN narrative, is often thought to have suffocated leads into the usual villains---the CIA, or others---but the instruction also snuffed out pursuit of leads into G2 or the KGB.
Moreover, we have had decades of people combing through available US documents and files, without conclusion...but who truly knows what is in Cuban or Russian files?
Or if any paper documents were kept regarding such an assassination?
My best guess is the JFKAC was a very small, two guys in G2 or Alpha 66, and the Alpha 66'ers could have been G2'ers or double agents. The pair worked with, or manipulated LHO.
Just IMHO.
Caveat emptor and draw your own conclusions.