Dawkins stepped out of his area of expertise. He is not well informed aobut trans peopel or trans issues.
He is very well informed about religion and atheism, and his misstep into areas he lacks actual knowledge doesn't take away form where he is expert.
Much ado about nothing. What he stated was factual. He didn't actually offer an opinion one way or another.
Minding Your own Business is a concept many need to learn!