Sure, in a gender agnostic, perfect world the correct pronoun would be their and we would use it in this case. But that’s not the world we live in.
You may or may not be surprised to hear this, but most of the language used to talk about developers is gendered as male. It might sound reasonable to address them as such considering that 88-92% of developers are male, but that’s partially why there are so few female engineers: exclusionary language. We keep talking about developers as male, and that’s a signal that women don’t belong. At the bare minimum we should talk about engineering as gender neutral, but we don’t and the damage has been done. Furthermore, explicitly labeling things as including women has a pronounced effect on women’s participation.
So the minor step of explicitly labeling the iOS developer as female in this announcement is actually very appropriate and we should use ‘she’ and ‘her’ when we talk about engineering.
Sorry if you care more about grammar than gender equality.