According to the New York City Human Rights Law, employers and other entities are required to use pronouns with which a person self-identifies, including singular they or neopronouns:
The NYCHRL requires employers and covered entities to use the name, pronouns, and title (e.g., Ms./Mrs./Mx.) with which a person self-identifies, regardless of the person’s sex assigned at birth, anatomy, gender, medical history, appearance, or the sex indicated on the person’s identification.
Most people and many transgender people use female or male pronouns and titles. Some transgender, non-binary, and gender non-conforming people use pronouns other than he/him/his or she/her/hers, such as they/them/theirs or ze/hir. They/them/theirs can be used to identify or refer to a single person (e.g., “Joan is going to the store, and they want to know when to leave”). Many transgender, non-binary, and gender non-conforming people use a different name than the one they were assigned at birth.
The Stack Overflow company is based in New York City, although I don't know if Stack Exchange is a "covered entity".
Is the Code of Conduct update announced 2019-10-10 in any way related to the legal situation in New York City?