The author isn’t doing anything systematic with “they” replacing he/she everywhere; it’s just that the main character uses “they” pronouns. For people who don’t

The author isn’t doing anything systematic with “they” replacing he/she everywhere; it’s just that the main character uses “they” pronouns. For people who don’t know anyone using “they” pronouns, a book like this can be a helpful way to get used to it—much easier than encountering it for the first time in the workplace. It’s true that when there’s singular/plural ambiguity, you do have to find strategies to resolve it. Luckily they’re similar strategies to how we resolve singular/plural ambiguity when using “you.” (It would be nice if English had kept “thou” around. Alas.)