The presence of the rifle is massively incriminating. It's the most incriminating piece of evidence there is. As far as I'm concerned, that's the point of the rifle - to be incriminating!
My rebuttal is that almost all the available evidence regarding who was on the 6th floor just before, during and after the assassination points away from Oswald:
Rowland, Roberts and Fischer all appear to describe the same man and that he was wearing clothes Oswald wasn't wearing and didn't own. Three independent eye-witness testimonies.
Euins is emphatic about the bald spot on the shooters head.
Garner never saw Oswald supposedly hurrying down the stairs - because he didn't hurry down the stairs, because he wasn't on the 6th floor at the time of the shooting.
He was in the Domino Room as he claims he was and this is confirmed by his observation of Jarman and Norman after they entered the rear door and were making their way to the west elevator. If they'd used the east elevator he wouldn't have seen them but it is because they had to walk around to the west one they came into view.
You can try and brush this all off all you want but it won't go away.
If Oswald wasn't on the 6th floor at the time of the shooting, and the available evidence dictates he wasn't, then the rifle was planted there to frame him. What possible evidence could there be for someone placing the rifle in it's hiding place? Film footage?
Nevertheless, he refused to identify Oswald and his reasons for not doing so are weak sauce indeed.
Wow. 
I'll ignore the more outlandish parts of this section of your post.
Brennan states that the man he saw on the 6th floor appeared much older than Oswald. That's that.
His description of the shooter's movements after the assassination contradicts the WC's account, which left barely three seconds for Oswald to get in position on the 2nd floor looking calm and not out of breath. That's that.
The presence of the rifle is massively incriminating. It's the most incriminating piece of evidence there is. As far as I'm concerned, that's the point of the rifle -
to be incriminating!You're absolutely correct....Dan. And the fact that Lee had Marina take his photo while holding a carcano similar to the carcano that was found where it had been well hidden beneath a pallet of books is also pretty convincing evidence that Lee owned a carcano. The TSBD carcano may, or may not, be the same carcano that Lee is seen holding in that carnival rendition of a photo......But it makes no difference because that TSBD carcano was NOT fired that day.
So taken together the presence of the carcano....and a photo that seems to show him in possession of that carcano is very difficult to refute.......BUT!!....Since I'm absolutely certain that Lee Oswald did NOT shoot anybody... that seemingly incriminating evidence is very convincing that someone was setting him up to be the patsy..... AND since it was the authorities ( The DPD and the FBI) who presented that lie to the public there can be little doubt about WHO set him up.