The facts and common sense tell us beyond any doubt that Oswald was on the 6th floor at the moment of the assassination whether in a CT or LN scenario. The LNer conclusion is based on the evidence Oswald left. The shots were fired at 12:30 from the 6th floor. Oswald left his prints on the SN boxes, bag, and rifle. Fired bullet casings from his rifle are found by the window from which multiple witnesses saw the rifle/gunman or heard the shots from directly above their head. Oswald has no credible alibi for this moment but is seen a couple minutes later in the 2nd floor lunchroom. The evidence places him on the 6th floor at 12:30 and on the 2nd floor a couple of minutes later. The only apparent means for him to go from point A to B is down the stairs. Because it was done without him being seen, that proves beyond any doubt that it could be done. It can not only be implied from the known facts and evidence but MUST have been what happened. All the pedantic nitpicking in the world in a desperate attempt to suggest doubt doesn't change the underlying facts and evidence. If Oswald fired the shot at 12:30, and was seen on the 2nd floor a couple of minutes later, that alone proves he was able to get down the stair unnoticed. There is no further prove of that necessary. CTer can disput the evidence that Oswald was the shooter, but not that he made his way down the stairs unnoticed if he was the shooter in the LN scenario.
In the CTer scenario in which Oswald is being framed, there is absolutely no plausible scenario where the conspirators would allow Oswald to roam about the building. It is absurd to suggest that after all the planning and risk to frame Oswald for the assassination of the president, that the conspirators would leave the most important thing to chance - whether Oswald would be in the presence of anyone who could give him an alibi or even be photographed on the street. How would they even know he was coming to work that day since he had made the visit to the Paine house where he usually spent the weekend? What does that tell us? That Oswald's movements in minutes leading up to the assassination would have been under the control of the conspirators either by choice or force. If Oswald had been forced by someone to stay on the 6th floor out of the presence of his co-workers, he most certainly would have shouted that to the heavens. Particularly after he was arrested for the crime. There is no logical scenario where he is taken by force to the 6th floor and never mentions it to anyone. That leaves Oswald perhaps working with the conspirators in some manner and voluntarily being on the 6th floor. Either way there is no doubt in this conspiracy scenario that Oswald is not in the lunchroom or roaming about the common areas of building of his own free will at the moment of the assassination. He is on the 6th floor. That means he made it down the stairs unnoticed since he is encountered there a couple minutes later. Once a thing happens, the odds against it happening no longer matter (even if they are accurately assessed which is not the case here with our pedantic Inspector Clouseau's analyzing the witness movements down to the second to reach a desired conclusion). If the facts, circumstances, evidence and logic all confirm that Oswald was in place A at 12:30 and place B a couple of minutes later and we know the only way to done so was down the stairs, that proves he went down the stairs unnoticed. A time machine is not required. Nor is it necessary to rebut laughable timelines based on witness recollections that would need to be accurate to within a few seconds. That is just going down another pointless rabbit hole.
The CTer mantra is to fixate on a single aspect of the case and ignore the implications of everything else including their own argument having any validity. How would they square Oswald sitting in the lunchroom in plain sight of anyone who passed by or perhaps deciding to go watch the motorcade on the street like anyone else with a plan to frame him as the 6th floor assassin? We will never know because they realize the absurdity of the consequences of their theories having any validity and refuse to extend the discussion beyond one single aspect. The focus is solely on a second-by-second analysis of witness movements as though there is perfect witness recollection, and all events were timed with scientific perfection.