I don't see evidence that Sirhan Sirhan was Republican, and Oswald was definitely a communist. It's not clear to me how that supports your point.
(As well, you may have heard of this guy, goes by the name of Ted.)
Ted never came anywhere near the presidency and then he sealed the deal with his little car accident; JFK was hoping for two terms, of course, to be followed by RFK, since they were the gifted ones. Killing Ted would be useful from the Republican POV, of course, since Ted did a lot of good work in the Senate, but Robert and John were the threats.
I don't see evidence that Sirhan Sirhan was Republican, and Oswald was definitely a communist. It's not clear to me how that supports your point.
The point is that each had a vastly greater impact on the politic...
A reminder for everyone: on this day in 1983, Stanislav Petrov saved the world.
It occurs to me this time around that there's an interesting relationship here - 9/26 is forgotten, while 9/11 is remembered. Do something charitable, and not patriotic, sometime today.