Yes, the administrator would have total control, can disconnect a user, etc. Typically, what you want to do when someone is signing up is to have the administrators not make it automatic, but verify that the person is part of the Union Community and/or some other interested party. We all know good folks in College Hockey that are capabale of adding a great deal to an intelligent discussion. For example, someone may apply for an account but they would have to give a reference to someone who is already a member. There are all sorts of possibilities. The Spammers would not be allowed to comment.
I think that this is the way to go. There is already an ability on the Union College Site to do a little of this. In other words, we could set up a special interest group, but the capability looks very limited.
I don't know if anyone here remembers the old "Majodomo" mail list manager but these web based message systems work off some of the same principles.
http://en.wikipedia.org/wiki/Majordomo_(software)
I could set it all up but would want one or more of you folks to serve as the administrator(s). It would not be a lot of work. I do a lot of consulting and an between "gigs" right now, so I have some time, to set it up. I could do any training with join.me