I would like to throw in my point that verbal abuse is never justified when in regards to D&D.
Now, if Fusangite had made disparaging remarks about a player, or in some way acted outside of normal social mores, I would say that such behavior may be understandable (not justified, but understandable). Otherwise, D&D is a game, and there is no reason to yell at your game master, just as one does not overturn a table after losing a game of checkers.
I myself am guilty of getting angry at a gaming table, however, one of my only goals in regards to gaming is overcoming this. It is not appropriate to get emotional over what goes on a gaming table (at least, no moreso than it is at a dinner table). Someone mentioned that RPGs require a more of an emotional investment than sitting down to eat a meal. I will not argue this point. However, I cannot condone yelling at another human being because of something that happened to a fictional character.
If you sit down at a gaming table, and the game-master changes a rule in the middle of the game (not that I'm saying thats what Fusangite did), the game master has done nothing worse than making a bad call. If a game-master kills your 21st level bladesinger, of which you have drawn your own 12 page comic book and included in a novel proposal, the game master is guilty only of insensitivity. However, if you then yell at the game-master and storm angrily out of the room, you are being immature. There is nothing in any WotC product that tells you how you should treat your friends.
Now, if you're part of a big boisterous group of friends who will scream at each other for a couple of hours and then go have a beer like nothing happened, then of course, I guess it makes sense to scream over D&D. But my point is that its a game, at the end of the day, RPGs are not matters of cosmic importance, and there is no excuse for mistreating another person because you don't like how they run their game.