User blog comment:Mathias Custos/Fandom unite/@comment-25555436-20150729010014/@comment-24891101-20150729022248

How does that follow? If it's correct, then definitionally it is the right use. English lacked a gender-neutral third person singular pronoun, and so at some point someone decided to use they, and it caught on, thereby becoming correct. That is how language works. Prescriptivists are morons.