I have often wondered after reading about Van Buran if the Vault set up in Salt Lake City for the Mormons was going to incite some sort of rage from the Mormon community. I think it very well could have incited some kind of rage from this group and caused a bit of turmoil if Van Buran had been released. How bad it could have been is anyone's guess. However, one sure thing that could have come out of this was a bonfire that would have sent the smell of burning plastic throughout the Overlaying hills of Central Utah. Now from what I have read of the town of New Canaan, it seems that J.E. Sawyer tried to not trample on the faith, but only use it as a plot devise for this particular city. I imagine that it more then likely was brought up as a way to implement faith in such a desolate place such as the wasteland, or the people in charge at Vault Tec figured the Mormons would have cannibalized their belief system and started bickering to the point where they killed each other off. I really would have liked to have seen this town in Black Isles Fallout 3, mostly to see how the Mormons would have received this title and how they might have felt about turning out like they did in post nuclear America. From the Mormons I have met in my life I would have to say that they, depending on there slant, could have received it fairly well. The question is how would the fanatical have taken the prospects of their faith being portrayed in a video game. Now this is only for the fanatics that used a computer of course. The Mormons that live in communities where Technology was shunned would have no idea this game even existed even if it did come out. The important thing to realize is that this could have lead to many different stories in the future. Sadly, we will never know what could have happened. It is however fun to speculate on how parts of the public would have received this element to the game.
There is a lot wrong with your assumptions about Mormons. They don't rage, they don't protest. The worst they would ever do is release a statement to the media, and if you have seen any of those, you wouln't post this things. Mormons don't kill each other. Mormons are WELL prepared for survival, and would, IRL, probably be better prepared than any vault in the area.