Is this mod for people who are triggered because the field isn’t free form and the only choices are he/she/they? Or people who are triggered because the sheer existence of a they option is an anathema to their existence?

People triggered because of a they option in character creation. Basically, for folks like this dude.

There is a prominent movement where people don't want to see LGBTQA+ people anywhere. They don't want queer people to exist in their world. It makes them very mad to be exposed to the existence of LGBTQA+ people.
I personally think that they are just some queer people in denial, thinking they are going to catch the gay. Those gay thoughts aren't going to go away for these people no matter how they cater their reality.