I'm not saying this is the case for Ross, but it's a possibility, at least for one of the contracts. Using violence to protect innocents is not something bad. It's just unfortunate he created the situation in the first place - instead of an extortionist, he may have confided in a LEO, thus hurting his users. (Which is apparently what happened.)
Anyways, the big lesson is that when your startup has major security requirements, go slow and don't break things. There's no real reason he shouldn't be retired now, enjoying his life while enhancing others. Just technical incompetence.
Another difference is scale. The extortionist that was after Ross was threatening to leak data on hundreds or thousands of innocent people. Do gangs usually find themselves in such situations?
If a gang is just selling drugs, not otherwise robbing or killing or hurting others, then I'm not very troubled by them killing extortionists, no. I just doubt that scenario makes up a notable portion of gang violence.