Corporate boards are mostly filled with 50+ year olds, and in those cohorts, there may be more men than women that fulfill the requirements.

(This is likely to change in the next generation, as women now generally outcompete men in tertiary education, sometimes wildly so.)

It is not too dissimilar from the familiar problem of Californian tech companies: they want some black programmers really badly in order to check some diversity boxes, but the pool of candidates leans heavily Asian.

Women will be aggressively recruited to fill the mandatory slots. Not worth looking for men at all, you don't need them unless they happen to be so good it's worth burning a slot on one.