The problem is that “Richard” has official narrative blinders on. He is incapable of operating outside of it.
Indeed. That's his biggest problem. He actually lost the argument some two months ago and still doesn't realize it. It's kinda sad, really.
Like any other fanatical zealot, Richard, can not imagine that his bible (i.e. the official narrative) could possibly be wrong.
Oswald not coming down the stairs unnoticed within 75 seconds after the last shot means that he wasn't on the 6th floor and thus that he could not have shot Kennedy from there. This would destroy a crucial part of the official narrative and justify the question what else there is in the official narrative that could also be wrong.
Obviously, Richard doesn't like or accept any of that, but he is not so dumb that he doesn't understand that he hasn't got a shred of evidence to put Oswald on the 6th floor when the shots were fired (as he claimed) so he falls back on his faith like belief and simply hopes he can BS his way out of the mess he has created from himself by deflection and making (in his mind) big issues out of non-issues.
"It's easier to fool people than to convince them they have been fooled” -
Mark Twain