Luigi was a very special situation of a man pushed to the limit after a botched medical surgery and decided to take action when he felt there was absolutely no recourse. Health Insurance is a genuinely evil industry, with far more blood on it's hands than any other industry you can come up with. He outright stated in his manifesto that he did not take pleasure in ending the life of another man an never wished harm upon an innocent person, and his decision to do this was something he weighed heavily.
Redditors saw this prinicpled man, and decided to compare him to a Video Game Character. Putting on stupid little mario hats and making memes about it. Putting edits on tiktok. And of course, they look at what he did and think it's the same to do it against a democratically elected official and the people he appointed, including autistic teenagers.
Redditors want him to be their folk hero, but they are mentally immature and if asked luigi would probably be disgusted by them.