Why is it childish to point out when someone is acting criminally — in a literal sense being a bad guy? Is it somehow more adult to act as though you are morally equivalent to an extortionist?
I think people might be being offended-by-proxy by a sort of status-shift 37s is trying to work into its language. Calling someone "an extortionist" still implies a sort of high-status white-collar cunning-and-intelligence, of the kind you'd expect of a person in the tech industry. An evil person, surely, but the respectable, movie-villain-you-love-to-hate kind of evil.
Calling someone "a criminal", meanwhile, degrades their status to that of a common mugger; someone in the lower class who needs to commit crime to survive, and who doesn't have the intelligence required to come up with a clever crime.
Hackers are generally aesthetes--we tend to value our intelligence, curiosity, etc. more than we value our moral fibre. We can appreciate stories like "A hacked into B to see if it was possible, and reported the vulnerability all responsible-like, but then they threw him in jail! How horrible!" because we think the positive-status from the display of intelligence makes it less likely, rather than more, that they were genuinely seeking to harm the people they hacked.
Because of this, I think we here are scared of being potentially associated with dumb, low-status, lower-class criminals more than we are of just being considered evil. People hire "evil, black-hat" hackers. Nobody hires a dumb hacker.
Calling someone a criminal degrades their status from someone who doesn't commit crime to someone who does. It degrades them from someone who adds value to someone who takes value.
There is moral judgement involved with calling someone a criminal, and rightfully so. Taking what other people have created by force or extortion degrades society.