Brennan wasn't "hounded" by anyone to confirm Oswald was the assassin. In fact, it's exactly the opposite, he explained that he did not initially ID Oswald as the assassin because he was fearful to do so.
So why didn't they lie and say he identified Oswald at the time of the lineups? Brennan could be "hounded" to say he did. If they "hounded" him to ID Oswald later why not "hound" him at that time? Or "hound" him to say he did? This was all a sham, a fraud, a setup of Oswald: the lineups were a lie, the identification by the witnesses were all lies. But they "allowed" Brennan to not identify Oswald?
The silliness of conspiracy believers is endless. The conspirators both frame and not frame people, hound and not hound people, do obvious things and not do obvious things, plant evidence but not plant evidence, coverup but not coverup. They are both incompetent and powerless and all powerful and in total control of events.
This is either some weird game they play - "JFK Assassination The Game" where you score points by coming up with the most original idea or claim - or the assassination is the vehicle for these people to express their grievances about the world, the US, "the Establishment", the CIA, the media, the police. For anti-American types - some of these people from the UK are a real hoot - it's the evil US as a whole, whatever monsters they have in their heads.
Multiple generations of Americans - Democrat and Republican and independent, liberal and conservatives, JFK haters and JFK lovers - have gone to Washington over these 60 years or so. They've served in the CIA and other agencies. From top to bottom and in between. And all of them - every single one - has covered up the government's role - the CIA most specifically - in the assassination. Why? There is no reason to do so. They would be recognized as heroes for uncovering this treason. But they didn't. They all have suppressed the truth.
This is, frankly, either gross ignorance about human behavior and human nature or a type of paranoid mentality. What's another explanation?