In itself, I couldn't care less what Izzard does in one role, but I do feel that this is exactly what many of us have been saying for ages. When men can say they are women and stamp on anyone who says differently, all the work that women did for years to carve out roles for themselves has gone. This is a role being taken from a woman in a literal sense, but it will spread to all sorts of others that are traditionally female, remove female categories in areas such as sport and destroy the very few female shortlists that still exist. At the same time, words like 'mother' are being corrupted to become 'gender-neutral'.
I note that Adele has been getting flak for saying that whilst she understands the reason behind having gender-neutral awards, she is a woman, and enjoys being a woman. As soon as I heard her say it I knew what would happen, and sure enough, it did. If women can't say they are women, but we have to say that transwomen are women on pain of being 'cancelled' (or worse), we really have fallen down the rabbit hole.