I really dont see either 'fixing' something that isnt broken.
Even if you remove all the AH people and the bazaar people, I would bet that it would still be crowded in juneo similar to how white gate used to be.
The best thing to do, would be to implament an auto-log off feature for PJ only where 60 minutes + of afk = log out. If your only goal is to reduce congestion that would cover all bases.