Don't be silly, that has nothing to do with sexism in tech and everything to do with sexism of a single idiot. I, for one, would be really happy to have a girl co-founder (I would be equally happy to have a guy co-founder, though).
That's great for you. But (if he wrote it) he didn't write that in a bubble. He wrote it in an environment where an overwhelming proportion of startups are founded by young white men. Put another way, a man in a rural southern town calling Obama the n-word is just a solitary act, but one cannot discount the racism of that man's peers in promoting the use of that word to describe black people.
