I don't disagree that Unitedhealthcare seems to be an egregiously terrible company that contributed to suffering on a wide scale, largely avoidably so, after having done some research.
If we abandon rule of law, though, we lose civilization. I would prefer sweeping health care reform over murder in the streets. Especially when a mob of emotionally volatile people can be convinced of virtually anything trivially, e.g., someone being an irredeemable piece of shit who deserves to die, regardless of the truth.
This time maybe you can consider it justifiable, but what about next time? Everyone with sufficient money and power will remain siloed from the rest of society, chaperoned by bodyguards, even more so than they already are. Let's not turn ourselves into a failed state.