JR members shouldn't be allowed to trade period. Then we wouldn't have this sandbox shit. Also: Who the hell would deal for 50 bars or 30BTC with a member with 40 posts.
Then we would have the same problem with "full" members, then "sr" members, then "hero" members... I can't stress this enough: Although it does act as a nice filter when dealing with potential scammers,
You should not base trust off of post count!