Great piece, John. You write the way John Oldman from Man From Earth would write if he wrote essays for Medium. Maybe you are him, because he always uses the name "John".
Anywho, I loved JFK while finding its conclusions absurd. Garrison was a nut. Prouty, the inspiration for Sutherland's "X" character, not a nut, but strange, nevertheless. I've never been able to find confirmation, e.g. for his comments regarding security for the President's visit to Dallas. Would all manhole covers really be welded shut? Much of Prouty's Weltaunschauung derives from a dubious source, the alleged destination of man-packs made surplus by Japan's surrender. Supposedly they were to be sent to Hanoi to aid Ho Chi Minh's forces against the French, thus US intelligence was playing a double game, conspiracies that continued to shape all US intelligence in his History of the Secret Teams.
If Prouty's full of crap, so is Garrison. But even a stopped watch is occassionally correct. So, who knows?
Oswald's lack of obvious. motive challenges some. By all accounts he liked JFK. But he also had some twisted notion of becoming a force of history, so who knows? As Mailer wrote, Oswald seemed to be about the last person you'd take into your confidence to part of a carefully-planned conspiracy. But then look at the other assassination conspiracy, against Lincoln. They were complete morons. That Booth was the highest functioning member tells you a lot.