The Mormon Church is notorious for misrepresenting their policies, doctrines, practices, history, etc. They refer to this practice as Lying for the Lord and consider it their sacred duty if the falsehood upholds their faith and the truth hurts. Proxy baptism is a classic example of an embarrassment where misstatements are legion.
Your notion that the practice of dead-dunking the ancestors of persons of the Jewish faith (and other people who find the practice repulsive) is due solely to a few rogue Mormons is incorrect and, quite frankly, extremely naive.
I’ve been called worse than naive. IMO this isn’t a political issue.