So they knew who really killed JFK and covered up for them? Them being? The Soviets? Castro? Rogue CIA? For political necessity at that time? And then the HSCA continued with this necessary coverup? The Church Committee? The news media?
You start with a plausible argument for the original coverup/suppression but then it all falls apart when you have to explain the subsequent coverups. By people who weren't even alive or very young at the time of the original crimes?
It's been a 60 plus year series of necessary coverups?
No. Gerald Ford said (to the President of France) that they knew that there was a conspiracy but they didn't know who was behind it. This couldn't go before the American public and the rest of the world so i all had to point to the lone nut at all cost.