I'm not sure, but I think you can't join a tournament unless you have created a profile pic.  I tried inviting a player who has no profile pic and they didn't show up in the queue - or at least I didn't see them in the queue. 

If a member is then inclined to join a tournament, they will be enticed to post a pic as well, so we should be able to invite them.

Edit: Hmm... Take it all back -- I see it there now -- More coffee please.