There doesn’t need to be a vanguard party for there to be a threat of violence… With more people becoming anti-capitalists and anti-imperialists every day, for better or for worse we’ll get more adventurists like Luigi and Tyler. While that’s unlikely to threaten the system as a whole, it’s clear that Kirk’s assassination hit very close to home for them - they’re not just afraid of the system being threatened, they fear for their own lives.