You can use this for any example of self defense though. If we accept that the CEO represented an imminent threat to Luigi and to others, then the self defense was justified. The same as how it is justified for you to murder someone who is pointing a gun at your head and is moments away from killing you. You don't need to wait for a trial in that case.

The idea here is that the US health insurance system represents a constant and ceaseless threat to the entire population; and, because industries like them write our laws, lawsuits against them are impractical. There have been legal challenges to the US Healthcare system; none have resulted in structural change. Given this, the actions of Luigi (or whoever did it) are the only remaining choice left to protect the American people from this deadly threat

Although I suppose emigration to a social democracy such as Sweden is also an option. But that isn't feasible for most people. And Sweden/Norway/Finland/Denmark/etc would soon ban immigrants from the US if hundreds of millions of Americans decided to suddenly move there