Sorry, was hoping to put more in the title, so I apologize if it is misleading. However, the possible exploit that I believe exists in one where a good member accidently walks into another good area. The tribal member can then attack the encroaching good player who cannot defend themselves (weapons pass right through).
Recommendation: If attacked, you should be able to defend no matter the alignment. In addition, make sure that if defending, no hit against your alignment should occur.