So the rifle wasn't being used to set him up as a gunman?
It was being used to set him up as a commie confederate?? (What's a commie confederate?)
On that scenario: as the supplier of the rifle (or one of the rifles).
Let's remember, Oswald was being announced as the assassin of JFK almost as soon as he was arrested.
Sure, but we're talking about a different phase of the thing here: again, we have to consider the assassination conspiracy as one thing and the cover-up conspiracy as another (albeit possibly overlapping) thing.
Think about it: if the conspirators' big plan was to make the world think Mr Oswald was at the SN window, they did a lousy job of sealing that particular deal. I mean, talk about amateur hour!