I think the legs apart issue with the elders was to determine the amount of willingness the victim displayed in the act of aggression by the raper. Then they could pronounce a guilt verdict on the victim in a judicial committee and discount her testimony.
So if she opened her legs wide would be an indication of willingness to receive advances by the perp thus negating her purity and perhaps highlighting her sinful nature as a possible seductress. Purely a heartless form of denial and shadow project of evil upon the poor lady in her predicament, in other words loving shepperds who will sacrifice the sheep on the alter of savage Deity worship which promotes corporation loyalty by cover ups.
And let not forget the admission of bribery to the mix as in one elder's response to the the victim as to this person;s paying some bill for him.