Jeff,
Not sure what occassions your post, but I do recall an incident some time back where a participant was sufficiently unruly that he was judged as unwilling/unable to play with the other children unsupervised.
I doubt that there is not clear agreement that at some level of (mis)behavior a participants access is best blocked or terminated, so I expect you are really questioning either that level, the means by which it is determined, or whether after a cooling off period they be permitted back in the pool.
Karl