This is LN "logic", right?
You say Oswald had no alibi, so he must have been on the 6th floor?
It's just more evidence, like the following;
Oswald has no alibi.
Oswald's rifle was on the 6th floor.
Oswald's rifle is exclusively linked to the shells in the sniper's nest.
Oswald's rifle is exclusively linked to CE399 and two fragments found in the Limo.
Oswald's rifle has matching fibers to Oswald's arrest shirt.
Oswald's prints were on the barrel and according to experienced fingerprint expert Scalice, on the trigger guard.
Oswald's fresh(within days) prints on the Rolling reader box, was moved over 40 feet and angled down Elm street as were Oswald's prints.
Brennan's description of the man he saw on the 6th floor is a close match to Oswald.
Other eyewitnesses report a rifle or a pipe like object in the window
Oswald is seen moving around getting a coke about 90 seconds later while just outside is total pandemonium, almost everyone in the building heard shots I wonder if Oswald did?
So as I said it's all about the evidence and without a bogeyman all you got is a lot of non focused nonsense and unconnected wild accusations.
JohnM