.... But the fact that you have this one member who has now emerged as something of a "leader" begins to make this take on the trappings of an on-line cult it seems to me.

Heaven forfend that it would get to this stage. But what if the "leader" suddenly began issuing orders to the followers to do something that could cause them harm? Call me paranoid. But I'd have to wonder what your website's legal exposure might be in a situation such as that. And, of course, you have to have concern for those followers who might come to harm in the process.