She. If you are unsure of a person's gender, just use 'they', but don't assume it's a man. In this case the pronouns are right there on the top of the blog though (as well used in the article).
Also, I cannot really explain really well, but it seems like there is a big difference saying “he” about just mythical person, and referring to a real person (whose gender you don’t know).
Not hard, but incorrect.