Your quote doesn't address the self-selection question. In fact, taking that paper, it suggests that males are about 30-100% or even more more likely to enroll

Your quote doesn't address the self-selection question. In fact, taking that paper, it suggests that males are about 30-100% or even more more likely to enroll in an ECS major across the range of math scores. For example, among those participants with a math score of 700, about 15% of females vs 30% of males end up enrolling in an ECS major.