A controversy that began with the arrests of two Boston University hockey players on sexual assault charges has mushroomed into a debate over women’s safety after a recent graduate called the school’s crisis hotline and found “a useless loop of automated menus.’’ Administrators said the hotline fracas stemmed from a misunderstanding and immediately took steps to remedy it. But women’s advocates said broader changes were needed to address the school’s “rape culture,’’ and they sharply criticized hockey coach Jack Parker.