This is just another example of faulty logic. A suspect does not have a "rock solid" alibi by claiming to have seen others. It works the other way. Someone confirms that they saw the suspect at a time and place that precludes them from having committed the crime. Even in your fantasy, it would still would not preclude Oswald from being on 6th floor. Four minutes is plenty of time to walk up a few flights of stairs or taken the elevator. The facts and evidence place LHO in the SN at 12:30.
"The facts and evidence place LHO in the SN at 12:30"This is incorrect and is the key weakness at the heart of the LN narrative.
Almost every piece of evidence pertaining to who was on the 6th floor just before, during and after the assassination points away from Oswald:
Three of the five witnesses who saw a man on the 6th floor at this time describe him wearing a white/very light coloured, open neck shirt. Oswald didn't wear such a shirt to work that day and didn't have one in his possessions.
Euins describes a distinctive bald spot on top of the shooter's head - something Oswald didn't have.
Dorothy Garner followed her work colleagues out to the back stairs in time to hear them rush down and was still there when Truly and Baker came up. There was no sign of Oswald supposedly heading down the stairs.
Oswald is reported seeing Jarman and Norman together. The only time during the lunch break that this could have occurred is when the two men came back into the building by the rear door. Oswald must have been on the first floor to witness this. According to their testimonies this can be placed around 12:25pm. The importance of this is that at least ten minutes earlier Arnold Rowland witnessed a white male carrying a rifle on the 6th floor.
Even Brennan, whose dubious and belated identification of Oswald is the single piece of evidence that places Oswald at the scene, describes the shooter as a much older man than Oswald. He also describes the shooter standing at the window, admiring his handiwork, as the presidential limo enters the underpass - in stark contrast with the WC narrative, which has Oswald rushing away from the SN in time for his rendezvous with Baker and Truly. In an indirect way this is supported by Hank Norman, who can hear the shells hitting the floor just above him, but doesn't hear anyone rushing away.
The facts and the evidence most certainly
do not place Oswald in the SN at 12:30pm.