If Oswald was being set up how could he be allowed to wander around the TSBD during the shooting? How could those doing the setting up control the TSBD, making sure they get in/out unnoticed and have a floor to themselves?
The last place they wanted Oswald was on the sixth floor. Whatever theory you want to offer must address the evidence that Oswald simply could not have gotten from the sniper's nest to the second-floor lunchroom in time to be seen by Baker.
The sixth floor was mainly a storage area and people were up there sparingly and intermittently, and the plotters knew it would be lunchtime and that many people would be downstairs watching the motorcade. Plus, the elevator was locked/not working so no one could use it to come up to the sixth floor. Furthermore, and this is a point that is often overlooked, the power to the TSBD got cut off just before the shooting occurred. Several witnesses alluded to this strange fact in passing, and one of them specifically mentioned the power being cut off, but, of course, the commission's interviewers failed to pursue it. The main witness to this was Geneva Hine:
Mr. BALL. Were you alone then at this time?
Miss HINE. Yes.
Mr. BALL. Did you stay at your desk?
Miss HINE. Yes, sir: I was alone until the lights all went out and the phones became dead because the motorcade was coming near us and no one was calling so I got up and thought I could see it from the east window in our office.
This is supported by the Alyea film. The film shows a light on in the entrance to the TSBD at the 2:03 mark, but this light not on in the Altgens photo taken during the assassination.
In addition, there is credible evidence that there were at least two people on the sixth floor during the shooting. This evidence includes the fact that the HSCA's photographic evidence panel determined from photos of the sniper's nest that someone was moving boxes around within 2 minutes
after the shooting: "There is an apparent rearranging of boxes within 2 minutes after the last shot was fired at President Kennedy" (6 HSCA 109). Obviously, Oswald could not have been the one moving the boxes around.