Was it necessary for Mormons like Mike Lee to post messages about how Mormonism is really another Christian denomination?
That whole thing about this not being an appropriate time to score theological/political points cuts both ways. Pretty much everyone is agreed that a great evil took place yesterday and are sorry for their loss. If guys like Lee are going to take advantage of that goodwill to insinuate themselves into the big Christian tent, then it merits a response.
Thee Mormons didn't even try to argue until a few decades ago that they're just one more Christian denomination. Joseph Smith's First Vision, a key LDS teaching, was that the Father and Jesus appeared to him and told him all the sectarian creeds were lies. They presented themselves as the one true faith. Until recently they had no problem with the use of the label "Mormon" (it was in all of their pro-family advertising back in the 1980s, for ecample). It was LDS president Russell M. Nelson (who died only two days ago) who insisted on the full use of the church name or "Church of Jesus Christ" for short rather than "Mormon church" or something similar--to emphasize inclusion in the Christian rubric rather than those profound and fundamental differences that make them very much
not us.