Here's the thing.
I think she's serious but I also think she's laying down a challenge.
It has been established in law that it is a protected belief to state that men can not become women because it's such a commonly held view and because of biological reality.
So if Labour decide to make a new law that using the wrong pronouns will land you in jail.
Think of the unintended consequences of this.
Imagine you have a 12 year old kid insisting they are trans. Then their parents refuse to use pronouns. The kid reports it to the police. Social services have to get involved and you end up with a pile of kids with parents in jail. Very vulnerable kids. What happens to them?
Or you have the rapist cases. Which I won't go into as it's been covered enough.
Or you have abused kids who are effectively criminalised if they state the truth.
Or wives who are in a relationship and this law is used to coercively control them.
Or you end up criminalising a bunch of doctors.
And above all else, I don't think the law will stand up in court well because it will clash with safeguarding and other rights. And you'll get a monumental cluster fuck which we and JKR can see coming a mile off.
JKR is a) drawing attention to say cluster fuck and b) effectively saying here, right take me to court, I'll lawyer up and it WILL be embarrassing for you Labour cos the publicity will be enormous.
It is a courageous statement and I think she means it and is prepared to martyr herself if necessary.
But it's also well calculated and grounded in the rational that should she be charged and taken to court it will cause 'scenes' and if it does end up with her being martyred and going to prison, the law will look so unjust to so many people, that there will be public pressure on Labour to sort the mess out.
She doesn't lose if she goes to jail. That's the thing.
Anyone with a brain cell in Labour needs to wake up. This woman isn't stupid.