Trust Levels
Have you considered making these users a higher trust level? For example, users who are Trust Level 4 can simply unlist/hide any topic they can see.
Watched Words
If there are words/terms that are common in the posts which need to be hidden, then Watched Words might also be of interest to you.
You could use Flag to allow topics to be posted, and then reviewed, or Require Approval which triggers the topic to be reviewed privately before it can be made public.