Received from Dave Wade at 9/4/2018 05:29 PM UTC:
As others have said, in most its usually people who need moderating, not topics. In most groups there are one or two vocal individuals who need careful management.
Yes... and they do so at their own peril in my groups. If they need "careful management" then everything they post is moderated because I don't have the time or patience to "carefully moderate" problem subscribers. If they behave as badly as you mention above... going as far as trying to open new accounts to bypass moderation, they get tossed and banned.
Responsible management can (and sometimes must) be supplemented, but never replaced. Every solution I've ever needed began with management of the root cause of the underlying problem... after which additional solutions were often unnecessary.