That's actually part of the progressive Christian argument — that many of the proscriptions in the Bible were culturally dependant and are not necessarily meaningful outside the culture they originated in.
Of course, that opens a can of worms, especially for conservative Protestants invested in "Sola Scriptura." Progressive Christians say they value orthopraxy rather than orthodoxy, which is partly where all the bitterness comes from in the ongoing UMC split.
The traditionalists who are leaving the Methodist denomination over what they consider to be the "heresy" of LGBTQ affirmation aren't just homophobic bigots, though some of them very much are. Their view of how the Bible forms (or should form) Christian beliefs is fundamentally incompatible with common progressive views on the subject, and progressives very much dominate the UMC today.
Thanks very much for this story. Hope to hear more from you from time to time!