Unfalsifiability problem: can we distinguish God's design from cultural accommodation?

If every instance of male-only leadership is explained as culturally caused, the theory is unfalsifiable — there is no possible evidence that could disprove it. Mike asks: do we have any way of telling the difference between God's preference and cultural preference? Egalitarians offer cultural reasons but, Mike argues, they lack actual cultural evidence — they only have the idea that women were expected to stay out of leadership.