If you can't understand why a lot of women won't speak out publicly, there's not much anyone can say, really. The threats are real.
Owen Jones is not as rich as JKR, but he is well-known, and has the media on his side. I'm quite surprised at his views, tbh, as he's usually pro-feminism, but the point is that he has a platform on which to make them - it's his job to tell people his political thoughts.
Women like the ones in the links are just doing their own jobs, but are being stopped from doing so because of their views. Two of them are in Universities - places where young people go to learn, and to be exposed to differing points of view, so that they can make up their own minds about things. Silencing those who teach them is a very worrying trend.
Similarly, Rosie Duffield is an MP - someone who represents her constituents. If she can't like a tweet (or other SM comment) and show people her opinion, how are her constituents meant to get help? There is no record of her ever having done anything against trans people, and no evidence that she thinks any more strongly than I do (and despite what you may say, I am not transphobic).
To say that nobody has to participate in the debate is either disingenuous or frightening. Would you have said the same to people in history who spoke out about injustice? Do you not support people's right to have their say without fear of retribution?