To be a Lower Class Hero and Icon you have to be Lower Class, yes.
Nobody called John Brown the Slave Hero or the living symbol of a Slave fighting oppression.
People’s perception of Luigi is fantasy fiction.
Have you ever heard of class solidarity? It’s not us = poor vs them = rich, it’s us = people who have to work vs them = people make money off us working. The fact that this “upper class” dude had to suffer at the hands of the healthcare system should have tipped you off that he’s one of us - the bourgeois don’t have to worry about healthcare.
You can praise Luigi for betraying his class but I don’t see any reason to replace the truth with fanfiction.