Are you sure that doesn't just refer to a preference for using 'they/them' as opposed to 'him' when it's a generic singular pronoun? People who knew her are using "her":
People often use pronouns other than the ones someone prefers for a variety of reasons: sometimes the preferred pronoun is new, sometimes people forget, sometimes people don't respect that person's preferred pronoun.
Without more context, even in that case, it could be either 2nd or 3rd person. Queen Elizabeth, for instance, might put her preferred pronoun as 'we', but you'd still write about her.
In any event, very sad.