GM's can only sort out the curse of ninja's if loot rules are publicly agreed in advance. To start i would suggest talking privately with raid leader so he can see and agree the rules below before he agrees to endorse them. If a raid leader refuses to follow these rules i would question why anyone would want to raid with that raid leader.
Macro 1
Looting Rules: 1. Players can only roll need on equipment they can use and for the role that they are currently playing, only if the group agrees and no player in that role needs can somebody roll need for off spec equipment
macro 2
2 - Failure of player to object to these conditions are taken as agreement to follow these rules and acceptance that in the event of a dispute a GM will be notified which may result in the redistribution of equipment if the item has been "ninjad"