This will be my final post in this thread, in all likelihood.
Anyway.
Best move for the involved shells, assuming they care about their rep, is to kick anyone confirmed on the list. Shows a dedicated stance against botting, blah blah blah, and plays well to the crowd.
Assuming that that is considered too much punishment for whatever reason, the option exists to basically sanction the individual in question. Strip them of all accumulated points, move them back down to the absolute bottom tier, etc. Give them the chance to start over again clean, but start over from nothing. Keep an eye on them, of course, to make sure they don't relapse. You'll lose some standing in the public eye, but some folks rank their friendships online as being more important than what people they don't know think about them.