JKR is really the personification of self sacrificing kindness.
She isn't kind to ranty men, or men wanting to use unconsenting others for validation or other reasons.
She is kind to the most vulnerable who don't have a voice, and she's painted a target on her own back and to a certain extent put her family at risk as a result.
Most people in her position would have selfishly stayed silent and enjoyed their millions. We see plenty of them doing it - who else stands up for the most vulnerable and disenfrachised in society like JKR?
She is the least likely person to be affected by the loss of women's rights. She can live in luxury until the end of her days. She's doing this for others, who can't do that. The women in prisons, the children, the women who've suffered domestic violence or coercive control, the rape survivors.
It's interesting how the definition of 'kindness' has morphed - it now seems to mean acquiescing to the demands of whoever shouts loudest, mostly men, no matter the damage to others.
I can't think of anyone in the public eye who is kinder or more self sacrificing than JKR