Rachel riley must be brave. My guess is she has read about this so is going in informed. Thay makes it less likely she'll back track. She obviously respects jkr and will have thought 'what's this about?' when it all kicked off. Plus she knows what online abuse is, has seen what jkr received for getting involved, so won't just be blundering in.
In her tweets since the article she is mainly standing up for Jkr's right to speak, and pointing out that the accounts who abused jkr for standing up against antisemitism are often the same ones who abuse her for her stance on womens rights.
But she also said, in a thread responding to India W:
"I think sometimes there is a conflict between women’s rights and trans rights, and there should room to discuss these things without being called a bigot, or without being called an extremist (for both sides)."
I completely agree with this.