It's not quite that simple. A number of the pioneers were openly bragging and taunting that they were parts of the mobs that had murdered, raped and pillaged Mormons back in Missouri and they they would do so again given the opportunity.
Isn't it interesting that films are made about the Mountain Meadows massacre, but none about Hans Mill.
Make one.
You have no source or evidence for that. While I do not condone the acts of those in Missouri, it certainly is explainable.
Along comes a religion that has more in common with paganism, led by a tyrant who has a lust for multiple wives. His doctrines & proclamations, fly from the cuff and have little basis in biblical theology. He boasts of a religious war and a desire to overthrow the US and establish himself in control. He was martyred by a mob that was fed-up with his antics and the fact that he had disagreed with an anti-mormon (ex-Mormon) Press, to the extent that he had the printing press dragged into the street and busted up.
Well, maybe I do condone what the missourians did . . .