See the point, but Utah is a worse location strategically speaking. Completely throwing them out of North American a la the Spanish Empire's deportation of Jews and Moslems is not really an option in the twentieth century. They have to be moved within the continentI dunno, deporting anI-American Mormons to anti-American Canada seems like a bad mixture.
There is no non Canadian island that is suitable and sending them to say the Great State of Houston would put them too close to the CSA.
Onreflextion within Canada, southern Manitoba is out
Given that it was not done in the second trilogy I don't think that a nasty enough president was elected so this is all theoretical so to speak.
Declaimer: I wish to state that in the real world I do not believe in deporting people just because they are politically inconvenient.