I get the idea, but considering that participation is voluntary, and one can simply leave or make a new community if one despises mods, leaving it completely unmoderated isn’t necessary to make it ancap.
However, it doesn’t even have to be organized in an ancap format for it to be a great way to talk about anarcho capitalism.  You can discuss chaos in a non chaotic environment.  
Likewise, you could discuss peace in a very aggressive unpeaceful manner, or discuss communism on private property.  Neither invalidates the shared ideas in those conversations.