We ALL know that JFK was killed as part of an obvious coup which installed Lyndon Baines Johnson but I don't really know about a "coup" in regards to RMN. True, he may have resigned or been forced to resign because he thought or someone told him they would reveal his complete involvement in the JFK coup. That makes sense to me.
The main premise of the Silent Coup theory is more personal and less political. The summary is that John Dean masterminded the burglary and the coverup, because his soon to be wife was involved in a prostitution ring, and the evidence of that was in the DNC offices. I've always thought that Nixon's involvement in the JFK assassination wasn't an issue and that he had no foreknowledge of it. Hoover, and to a lesser extent, LBJ, are a whole different story. I will concede though, that Nixon was in Dallas on Nov 22 1963 in his capacity as an attorney for Pepsi.