In other words, you're judging the morality of their actions purely by their impact upon those who suffer at the hands of society's injustice. But what if they were to bring harm to someone entirely uninvolved? For example, those police officers who do their honest best to uphold the law suffer if people lose faith in the criminal justice system.

The Phantom Thieves claim to be allies of justice, but they are, in truth, rivals to those of us sworn to uphold it. After all, vigilantes act behind the backs of law enforcement. Rather than seeing their actions as a success for the good of the country, they see them as a failing of the institutions they're supposed to be able to rely on.