I've never watched any Oliver Stone Xhen so keep your McCarthyite assumptions to yourself.
Not sure what the Oliver Stone comment has to do with McCarthyism other than as a catch all insult used in the absense of a logical fact-based response.
If it suits your eschatology to believe the assassination of the American president was left wing go ahead but don't expect many believers outside your hermetic little world.
My hermetic little world also includes virtually all American law enforcement agencies involved in the case and anyone who has studied the facts without an ideological axe to grind.
The case against Oswald has actually grown stronger over the years through the use of modern investigative techniques and technology. Computer models used to determine the path of the so-called magic bullet which wounded both Kennedy and Connelly and the fatal head shot have shown beyond much doubt that the shots came from the sniper's nest window on the sixth floor of the Texas Schoolbook Depository.
The fact that Oswald was a pro-Castro sympathizer has been well-established through documents, photos, and his own words during a televised debate. Claims that he was some kind of right-wing double agent or patsy are the product of convoluted conspiracy theories involving leaps of logic and faith. IMO, these conspiracy theories invented by the left are at least partially motivated by the fact that a liberal icon was murdered by a leftist. It's inconvenient to their world view.
For what it's worth, I don't think Oswald's ideology had anything to do with why he assassinated JFK. He was, first and foremost, a self-absorbed narcissist with an inflated opinion of himself. He was bitter that society didn't recognize or reward his intelligence and abilities and decided to make his mark on history by shooting someone important. When his attempt to kill General Walker failed, fate provided him the ultimate target by routing the President's motorcade past the building where he worked. The president's party and politics were largely irrelevant. If Nixon had won the 1960 election and it was his motorcade that was routed past the Texas Schoolbook Depository, Oswald would have undoubtedly been in that same window with his rifle. The assassination was about him, not his target.