It is bad. We have a society of laws and justice that's supposed to prevent the need for vigilantism. That system has broken down and favors people of wealth, and thus you have a return of vigilantes being seen as heroes.
vigilante justice is bad because you are enforcing a personal rule of law. the uhc ceo was enforcing many of his own rules through the company's own treatment of claims and its effects on governing entities. there was no justice, simply a warning that noone is less mortal than the people they commodify.