I may be a little slow and missing something, but here are my jumbled thoughts.

I found moral nihilism convincing for a brief time. The argument seems convincing: just about any moral statement you can think of, some people on earth have rejected it. You can't appeal to universal human values... we've tried, and I don't think there's a single one that has stood up to scrutiny as actually being literally universal. You always end up having to say, "Well, those humans are aberrant and evil."

Then I realized that there must be something more complicated going on. Else how explain the fact that I am curious about what is moral? I've changed my mind on moral questions -- pretty damn foundational ones. I've experienced moral ignorance ("I don't know what is right here.") I don't interact with morality as a preference. Or, when I do, sometimes I remember not to, and pull myself back.

I know people who claim to interact with morality as a preference -- only "I want to do this," never "I must do this." I'm skeptical. If you could really have chosen any set of principles ... why did you happen to choose principles that match pretty well with being a person of integrity? Quite a coincidence, that.

It's the curiosity and ignorance that really stumps me. I can be as curious about moral matters, or feel ignorant about moral matters, as about anything else. Why would I be curious, if not to learn how things really are? Is curiosity just another thing I have a preference for?

But It's weird to talk about a preference for curiosity, because I'm not sure that if you say "I want to be curious" that you're actually being curious. Curiosity is "I want to know why the sky is blue." It refers to something. I doubt it's coherent to make a principle of curiosity. (Curiosity is one of the Virtues of Rationality, but it's understood that you aren't curious by force of will, or by deciding to value curiosity. You're curious only if you want to know the answer.)