It's probably no coincidence that many conservative. Christians like some of the people who run LifeSite News buy into a sort of religious conspiracy theory that the United Nations is a Satanic or quasi-Satanic organization that the anti-Christ will use to exert dominion over the world in soon-to-come end times. Hal Lindsay popularized that view decades ago in his Christian prophesy bestseller "The Late Great Planet Earth," which led to a popular series of novels and films called "Left Behind."
Conservative Christians are conditioned to view the U.N. as evil and even Satanic, so it's not at all surprising that they twisted the meaning of this document out of all recognition — especially when they see a message that looks tolerant of any kind of sexuality outside of marriage.
The conservative Christian "abstinence-only in sex education" crowd abhor the very idea of teaching consent, claiming that it encourages sex. Combine that with their bugaboo, the U.N., and they lose whatever is left of their marbles.