Ninja Looting - Unique Way

I experienced a ninja looter in ICC who was able to bypass master looter and changed the looting rules to Free for All right before the boss died. He ninja-ed the item he wanted immediately and left all the other items bugged - binds on pick up permanently and unable to trade to any other raid members. Anyone has come across this and have any ways to prevent such occurrences again?

P.S. the loot rules werent visibly changed from Master Looter to Free for all i.e. the yellow system text did not appear, but any raid member could take the loot from the boss corpse...

It's just a way of how this game works.
If someone abuses this, you can make a recording and report it.

I always record every run.