Bitter you raise a good point, which is why this is being left open for debate before we do anything. If you've ideas how we could approach this without segregation (which I would hope wouldn't happen) being a concern.
Honestly, I didn't think it needed approached. I am not sure what you are trying to gain.
Either you are trying to create a "safe space" for young adults, where they are expected to be coddled, and supporting that with heavy handed Mod action, OR you are trying to incorporate them into the site as equals to be treated as equals. I think so much comes down to personality and expectation of the younger user for the latter. (I am not even going to use the word maturity here, cuz, well, you know)
Like that kid from the UK that posted recently, that asked how to sell more photos, and never replied for any number of reasons.
How would that thread have been handled in the "Kids Club" area? Was he ready for the truth? Could he handle the truth? I don't think the replies overall were rude. Most of them were honest and helpfull, whether that's what he wanted to hear or not. So the question to you is, what should be done differently in that example? Would he have been better served with a seperate section, or careful moderating of the responses? Would the responses have been different in the young adult section?
Should the responses have been different?