Yeah it might be a good idea if a user has a trust flag and at least 10 more supporters than opposers on it...
But can't newbies pm newbies so they could just make a new account?
It will definitely create an influx of newbie accounts. I do not think that this is the cure-all solution, my solution would be IP banning if that is possible. Most games that I play do this when they detect cheaters in their game, it is pretty effective because the rate of cheater drastically gone down. Although in this case, it will be different, I do not know much about the administrative functions in this forum so I do not know if it is entirely possible at all.