Thanks Keri. I think you're half way there in what you suggest. There is a distinction between a good answer and a question/answer the submitter would want others outside of mozzers to find. You can have one or the other or both.
What I am suggesting is that you simply allow the person asking the question to decide if it should be found by the search engines.
If we are talking about issues specific to an industry, brand, website or specific URL we often may not want that discussion to appear on the radar of people tracking the same. I am sure I am not alone in this.
Site visitors at seomoz.org would still be able to search for, read all Q&A etc. but by giving the OP a choice to disallow indexation, you are removing the likelihood of those outside of this community finding a conversation(s) that may strongly prefer not be open to the world.
I like the quality assurance aspect also (good answer, endorsed by staffer), but serves a different purpose. It would be not difficult to have both I think. Include a checkbox that is checked by default that says "allow this post to be be indexed by the search engines" and you can still implement your Q/A process for what appears on seomoz in Q&A, but allow OP to decide on indexation.
SE