No one is trying to have it both ways.
These are your words from a few pages ago:
“Oswald was a nut. Nuts don't have neat "motivations" for their actions. They don't behave in the same way as normal people. So it is not surprising that Oswald's "motive" remains unclear.” On one hand you dismiss speculation about his motive as irrelevant.
On the other, you seem to have a theory about his motive.
Motive doesn't have to be proven even in a criminal law trial. If there is abundant evidence to convict, then we know that person is responsible. That is the case here.
We’re not in a courtroom.
Everyone here is allowed to speculate about different elements of the Kennedy assassination but if the speculation isn’t based on reality or facts then some people will push back.
Oswald was attracted to Marxism, in large part, because it was a fringe political element in American society. That aligned with his own feelings of being an outsider. He was also considered unique for purporting to be a Marxist. It garnered attention including requests for interviews. Something that would never have happened if Oswald was a member of a mainstream American political party. To what extent he was a true believer in Marxist ideology is unclear. It aligned with his own fantasy to be someone important. How deeply he believed in the ideology can never be known. He certainly wasn't willing to stay in the commie utopia of the Soviet Union when it involved freezing his arse off and doing menial jobs. So a logical inference is that the depth of his political leanings were superficial but still important as a vehicle for his actions. His fanaticism was mostly in himself. He was an angry, disgruntled person who wanted to cause harm to the social and political system that he blamed for his anger about his lot in life. He didn't want to view himself, however, as an angry nut. Better to spin his impulse to commit violence in terms of a political act. So that was a fantasy he concocted in his diseased brain. That he was a revolutionary figure with a noble goal rather than an angry loser. Marxism was vehicle he used. He may have to believed in it for that reason but could easily abandon it when it didn't align with his own self-interests.
Fair points
I agree that it’s unclear how dedicated Oswald was to Marxist ideology.
I do believe he was broadly a Left-leaning Contrarian based on his own writings and the stuff George DeMorhenschildt said about his conversations with Oswald. But not a diehard Communist.
I’m not convinced that he could’ve been motivated by devotion to Castro or Communism.