I've known my type for a long time now.
I think the implication is that I think I do good by vehemently opposing the system (not that you're saying that that represents the entirety of why I think I am good, but I think it was one of the implications [nor do I take offense to it])... I think that is one way in which I might try to do good, but I think I only do that when I think the system is working in opposition to the good. That's where I agree with what @skylights said before: I think the system is supposed to promote the good, but sometimes it runs afoul of that mission. When it does, if it's something that irks me enough, I will oppose the system on those grounds. Good > Lawful. Hence, Neutral Good.
There are many other ways completely unrelated to system-opposition in which I aim for the good, though.
Both enneagram and MBTI.