JFK was apparently a big fan of the AR. His Secret Service detail was occasionally armed with them, and he kept one on his boat.
Since most U.S. Presidents, prior to Jimmy Carter, were not anti-gun if not actually pro-gun, Colt made fancy engraved guns for presentation to them. The one for JFK was not ready yet at the time of his assassination, so the gun was never presented.
I'm sure Carter, Clinton, and Obama all avoided the horror of being presented with an engraved, gold inlaid commemorative from the Colt custom shop.
The anti-gun legacy of the Kennedy family did not start with JFK, but probably with his death.