A lot of people on "our side" did a bad job of simply refuting the argument presented. Its straightforward to do in one sentence:
"While there may be scientific evidence of differences between men and women, using these differences to conclude that women are biologically less inclined to engineering is a gross leap in reasoning that is not at all supported by the facts."
Then you can go on and explain why for historical and societal reasons putting forth this weak theory is highly offensive and damaging to a large group of people.
Of course, many feel that you shouldn't _have_ to explain this to people, but unfortunately in todays environment, you do!
"While there may be scientific evidence of differences between men and women, using these differences to conclude that women are biologically less inclined to engineering is a gross leap in reasoning that is not at all supported by the facts."
Then you can go on and explain why for historical and societal reasons putting forth this weak theory is highly offensive and damaging to a large group of people.
Of course, many feel that you shouldn't _have_ to explain this to people, but unfortunately in todays environment, you do!