…I found your explanation verbose. Simply scream, and leap. Seriously, man: if you have problem commenters, get rid of them – especially if they’re costing you money. At the end of the day, this is a property rights issue, and the person who owns the property is the only one with the rights. Besides, there’s nothing better than a good banning.
Not that I would know anything about that, of course.
Pointed out by Constant Reader BigGator5.