“...not somebody who was trying to achieve a political goal.”
Why do you say that, x?
I guess it was the comparison to the New Left. Crazy or evil as it may have been, the Weathermen and others actually thought their acts were going to bring about a revolution -- or at least end a war.
I doubt Oswald thought his shooting would bring about a revolution. Could he seriously have thought replacing Kennedy with Johnson would end the Cold War?
Czolgosz, who shot McKinley, was one of several turn of the century anarchists who killed royals and politicians for political or ideological reasons, but I don't see that as quite applicable to Oswald, either.
Clearly Oswald had a lot of political ideas swimming around in his head -- he described himself as a Marxist -- but what would the end result have been? To replace Kennedy with Johnson? For that reason, I see personal factors at work in the assassination that make it harder to boil down as purely political.
The attempt on Walker could have been something purely political. Killing Tippitt was spur of the moment. Killing Kennedy may have been more complicated.
Greenfield goes in that direction when he brings in Charles Whitman, the Austin tower shooter, but then reels back to make a more purely political point.