Chuck,
As per Say Again Slowly's comment, I would doubt that increasing the moderator workload would be a good move.
From a technical point of view, the underlying forum software does seem to have a few features which mirror your proposal...
vBulletin Manual - User Reputation
...but I have seen forums where this has been added, and subsequently deleted; you can get some wierd kind of forum beauty contest dynamics being caused as a result.
From an orthogonal perspective, I have seen that the concept of a forum 'Sin Bin' can have some positive results. Forumites who, on the face of it, seem purely to have an antagonstic, aggressive or simply attention-seeking agenda are confined to a closed forum wherein they can only interact with a set of moderators. I have no idea of exactly what goes on in there, but either the reprobates emerge as chastened forum citizens, or they don't emerge at all.
For Pprune, I think the problem of accreditation is probably more acute in the mainstream Professional forums - given that they do seem to be the first port of call for journalists looking for copy, and often opinions expressed there can appear in the news media without any real verification of the credentials of the source. Minor perturbations in the calm waters of Private Flying such as we have seen recently are arguably small beer in comparison.
You can, however, count on my vote should the approach you suggest be taken up by the management.
Ed.