The beauty of the /roll system is that the highest roll wins. It has no logic to it, and is very inefficient if you're trying to gear a guild up to maximize your raid experience. That having been said, you didn't deserve the weapon since you lost the roll. I'm sure a lot of people will disagree with me on this, since it's pretty clearly one of the best weapons a warrior tank can get. Personally I think the current reward system for bosses is retarded, and only feeds the childish behavior we see so often in game and on forums.
It's a pug, and that's what you have to expect from people. Your ML probably didn't obey the rules set out in the beginning of the raid very well though.