Let's start with this question:

###1. How can we avoid the problems policing gender expression religion has brought up?

On religious sites, people post answers purportedly from their sect. Moderators (and diamond moderators) determine whether or not their sect is genuine (keep the answer), or whether it's just same random user on the internet with their own personal religion (delete the answer).

This is proof of concept that moderators already make decisions about boundary problems that relate to "I identify as" issues. In essence they act on their opinion: Is that a real religious sect? The risks of false positives and false negatives exist here too.

I understand the standard for determining if a sect is real is: there exists a webpage written about that sect that is not by the poster. It's very much in favor of giving the benefit of the doubt, but without totally switching off one's brain.

###2. How do medical professionals determine if someone is genuinely transgender?

The usual way of determine if someone is genuinely transgender (as opposed to it being a whim, some kind of fetish, or being a manifestation of a mental illness) is:

1. Consistent. It's not a new thing.
2. Insistent. It's not a minor thing.
3. Persistent. It remains over time.

Indeed, transgender people get grumpy at medical professionals for "gatekeeping", but this is the standard approach.

###3. How can we avoid the problems policing gender expression has brought up?

1. Don't switch your brain off.
2. If there exists a website describing this gender expression written by someone other than the poster, take it seriously.
3. If it appears consistent, insistent, and persistent, take it seriously.
4. If someone's using some unique neopronouns with no indication that it's a sincere belief (have they ever even used the pronouns themselves?), it's probably a troll.
5. If someone is misidentified as a troll, apologize and make corrections. They should understand because they will be negatively affected by trolling more than anyone.
6. If someone is genuinely misgendered, it's hurtful and embarrassing, so the last thing they would want is to draw attention to it. If they're making a big stink on meta.SE, it's probably a troll: trolls want the audience. If they want it discreetly settled and to quickly move on, it's probably genuine.

Let's start with this question:

1. How can we avoid the problems policing gender expression religion has brought up?

On religious sites, people post answers purportedly from their sect. Moderators (and diamond moderators) determine whether or not their sect is genuine (keep the answer), or whether it's just same random user on the internet with their own personal religion (delete the answer).

This is proof of concept that moderators already make decisions about boundary problems that relate to "I identify as" issues. In essence they act on their opinion: Is that a real religious sect? The risks of false positives and false negatives exist here too.

I understand the standard for determining if a sect is real is: there exists a webpage written about that sect that is not by the poster. It's very much in favor of giving the benefit of the doubt, but without totally switching off one's brain.

2. How do medical professionals determine if someone is genuinely transgender?

The usual way of determine if someone is genuinely transgender (as opposed to it being a whim, some kind of fetish, or being a manifestation of a mental illness) is:

1. Consistent. It's not a new thing.
2. Insistent. It's not a minor thing.
3. Persistent. It remains over time.

Indeed, transgender people get grumpy at medical professionals for "gatekeeping", but this is the standard approach.

3. How can we avoid the problems policing gender expression has brought up?

1. Don't switch your brain off.
2. If there exists a website describing this gender expression written by someone other than the poster, take it seriously.
3. If it appears consistent, insistent, and persistent, take it seriously.
4. If someone's using some unique neopronouns with no indication that it's a sincere belief (have they ever even used the pronouns themselves?), it's probably a troll.
5. If someone is misidentified as a troll, apologize and make corrections. They should understand because they will be negatively affected by trolling more than anyone.
6. If someone is genuinely misgendered, it's hurtful and embarrassing, so the last thing they would want is to draw attention to it. If they're making a big stink on meta.SE, it's probably a troll: trolls want the audience. If they want it discreetly settled and to quickly move on, it's probably genuine.