Their system seems really fair to me from an outsider perspective, not sure why everyone is attacking it.
I would think that when you join a dynamis shell you declare a main job that you will be lotting af for, you arent allowed to randomly lot af for multiple jobs (unless no one's main needs said item and it goes to free lot among other members with that job).
Also remember once a player recieves an af piece he cannot recieve it again. Once the rightful sam got his body it would be open to the next tier. Its not like he has a monopoly on the item, just on the first drop. As more of the item drop it will progress down the tiers until everyone has it then free lot.
As for the OP, wow what a shitty thing to do. I'm sorry that happened and will definately make sure I don't end up in dynamis runs with this individual. To his/her LS-mates in the social shell, I don't know this person but i hope you guys don't just ignore this like it never happened. I am not saying kick him/her, but don't pretend everything is fine. There really is no excuse for this kind of behavior and in a game like this where so much of our play relies on each other, breaking trust should not be free.