I think the key here is when you detect that someone is in a bad category, you shouldn't alert them to the fact you know that, because then it just becomes an arms race.
Another approach might be to make it look to them like they managed to create their blog, but just quarantine the content so no one else can ever see it.
The author mentions that they were basically already doing that by no-indexing the content. Plus, that can end up costing you more money hosting the quarantined content.
Another approach might be to make it look to them like they managed to create their blog, but just quarantine the content so no one else can ever see it.