I think you are letting your theological objections to Mormonism color your thinking. There is nothing un-American or unconstitutional about a religious organization ex-communicating a member over a theological dispute.
Criticize their theology all you want, but they are well within their rights.
But it isn’t theological debate, they have voilated their own Handbook of instructions in at least 12 points, lied to the public about who is behind this purge and her only ‘crime’ is not shutting up but standing for what she believes and that has historical precedent in the LDS church. She is a problem that must be silenced and they are holding eternity over her head. That is UnAmerican (there is no freedom of speech or thought in Mormonism) and very Un Christian (of course we all know Mormons aren’t Christians but they claim to be).
Now there is no freedom of speech as it relates to private organizations, however by violating their own rules (the CHoI) they are guilty of defamation, false light, and libel for falsely accusing her of several things. If this affects her ability to perform her job (as a civil rights lawyer) or has other negative impacts on her they can and should be held responsible.
BTW, in cased you missed it, the LDS church was caught lying about her and the role of the leadership in SLC in her excommunication.
You are absolutely RIGHT!
There is, however, something HYPOCRITICAL about it.
“There is nothing un-American or unconstitutional about a religious organization ex-communicating a member over a theological dispute.”
Correct and there is also nothing un-American about us discussing it.