Literary criticism of JKR's writing is totally irrelevant to her opinions on transwomen.
But it's interesting to see it unfolding; young, impoverished, abused woman writes several best selling novels and becomes a national literary hero and is recognised for her generous donations to humanitarian causes. She makes one initial statement pointing out the biological fact that humans cannot change sex. BOOM! She's an arch enemy of the transgender community, she's transphobic, she deserves to die along with her family, she, and all she stands for should be cancelled. And the latest insult..... She's a crap author anyway and is guilty of plagiarism of other writers.
This leads me to believe that JKR is hitting all the right nerves, in all the right places. When her detractors have nothing left to assault her with, they turn to her professional successes. I pity them