I don't know, but I think the answer is not obvious and this is a discussion worth having. Which is, arguably, exactly what the guy who wrote this memo was trying to do.

There IS well-established scientific evidence for differences IN THE DISTRIBUTION of areas of interest and specific abilities between the sexes, although even /that/ is apparently too taboo to discuss in this day and age. How big an effect this has on the gender bias in specific professions is a much harder question, although personally I find the assertion that it is "none" difficult to accept without overwhelming evidence.

Add on to that the question of how to correctly tackle this bias and you've got an even more divisive topic, as now you've layered on an ideological issue on top of a difficult-to-isolate research question on top of a scientifically well-studied but publicly controversial topic. Unfortunately, this is the issue the author of the memo tried to address.