Rarely is there an occasion to use someone's 3rd person pronoun directly so I don't understand why this is even an issue. What if we started using their preferred 3rd person pronouns against them instead of 2nd person pronouns? It's very degrading. After all, they're advertising their preferred 3rd person pronoun, but not their 2nd person preference. If your email signature includes him/his, I will call you him/his directly instead of you or your name.