This seems to assume that women must magically all have the same personality type and/or no personality selection bias in their career choices. Since women are comfortable going head-to-head with alpha-male lawyers, they therefore should be totally comfortable with geeky programmers. I don't buy it -- all women are not the same, just like all men are not the same.
It seems to me that women who become lawyers or businesspeople likely have A-type personalities themselves. Accordingly, they are probably more likely to view competition or confrontation with males in the workplace as a motivating challenge. Women who become programmers are probably, just like male programmers, a bit more introverted and geeky. Accordingly, confrontation/competition with males in the workplace is probably less likely to be motivating, and more likely to be intimidating -- especially when you consider that many "meek" male programmer types tend to drastically overcompensate for insecurity in physical situations with hyper-competitive and vitriolic behavior in virtual environments (I wonder what the gender and programmer/non-programmer ratios are like on 4chan).
In other words, just because male programmers don't rank as alpha-males relative to the general male population doesn't mean they don't behave like alpha-males in their own environment, especially relative to the female personality types interested in becoming programmers.
My 2 cents.