I believe the parenthetical “Fundamentalist LDS-cult” is an inaccurate and unfair association of FLDS with mainline Church of Jesus Christ of LDS.
FLDS is “LDS” in the same way as Fred Phelps is “Baptist” . . . which is to say, not at all.
Actually, FLDS practice what is in the BOM and also in Mormon history.
Your analogy about a "Baptist" who goes around saying "God Hates (fill in the blank)" is easily refutable, because Baptists can point to the Bible and point out how Phelps doesn't follow the teachings of Christ.
The same cannot be said to so easily divorce what the FLDS church practices, and what the BOM and Joseph Smith's own history and practices stand before us as facts.