This shouldn't be an argument, rather, the understanding of another's ideals and opinions regardless of how they conflict with one's own.
Whether this is sarcastic or not, the problem with MrSimon's assumptions is that they ignore the ~15% of women who are employed/unemployed within the industry.

For better understanding through a similar situation in regards to numbers, let's take a look at the United States's CIA World Factbook page.
12.85% of the population are black, compared to a 79.96% being white and 7.91% being of other ethnic groups. Is it fair to assume that all Americans aren't black, and are white instead? No, of course not, because despite the majority being white, 1/5 are not white. Less than 3/20ths of the US population are black!

Keeping this in mind, females make up ~15% of the workforce in the programming industry. This is around ~3/20ths of the industry. This is more than the amount of people who are black in the United States. To assume that because someone is a programmer, they are a male, is the same to assume that because someone is an American, they are not black. Obviously this is not the case, so it shouldn't be the case to assume someone is female/black if they identify as a programmer/American.