I've *never* seen a fixer break group to loot the boss.
Maybe I just team with good people or something.
Now, the other part of the problem, making it no-drop so that people will let the fixer have it instead of ninja-ing to sell, I understand that. But that's really a bigger problem, ninja-looting. And at least this way, if there isn't a fixer in the group, a fixer will (eventually) get it, even if it is an alt fixer.