"them/they" is also proper English, and although he and I might differ on how firm we are about the usage of pronouns, I agree with most of what he wrote there and think it's commendable that he's trying to make at least a small difference.

At least one chapter of Beautiful Code that I can recall used the random he/she pronoun strategy, and it's distracting and hard to follow.

Making software development sound less overwhelmingly masculine is probably a good idea.