But the reason why they think it had to be done still matters. "This CEO wronged me personally" and "the systemic oppression made me do it" contextualize the act in a very different way. The reason he did this is why it's political. If he had done it because he had a personal vendetta against the CEO or he had some religious beliefs that made him do it or if he was just insane, then it wouldn't be a political reason. But he did it because (paraphrasing his statement) he saw an unopposed corrupt system that needed to be opposed. That is a political reason.
If the intent of the killing is to change the system or have political outcomes, then it is political.
We have no indications that Luigi wanted anything other than one or maybe a handful more dead CEOs. That does not have political outcomes. Nothing has changed.
Because he considered them evil parasites for the work they're doing. Work that is still legal now after he killed one, because killing one doesn't have any effect on the governing laws and overarching system.
You said intent not outcome. Him killing only one and it "not having any effect" is an outcome. His manifesto doesn't say he intended to kill only one, his intentions were against the system not a single individual.
Looking at the outcome and saying "that wasn't political" is like saying Jan 6 wasn't political because they failed to overthrow the government.
I don't know what you're lacking to not understand his manifesto and I don't care because it's not my job to improve your failed education. I'm not wasting any more time on you.